Document:

EX-10.2

 Exhibit 10.2 
  

2015 STOCK INCENTIVE PLAN 

OF 

DECIBEL THERAPEUTICS, INC. 

 
  

  
 i 

 TABLE OF CONTENTS 

 

							
	 	 	 	  	Page	 
	 1.
	 	 Purpose
	  	 	1	 
	 2.
	 	 Eligibility
	  	 	1	 
	 3.
	 	 Administration and Delegation
	  	 	1	 
	 (a)
	 	 Administration by the Board
	  	 	1	 
	 (b)
	 	 Appointment of Committees
	  	 	1	 
	 4.
	 	 Stock Available for Awards
	  	 	2	 
	 (a)
	 	 Number of Shares
	  	 	2	 
	 (b)
	 	 Substitute Awards
	  	 	2	 
	 5.
	 	 Stock Options
	  	 	2	 
	 (a)
	 	 General
	  	 	2	 
	 (b)
	 	 Incentive Stock Options
	  	 	2	 
	 (c)
	 	 Exercise Price
	  	 	3	 
	 (d)
	 	 Duration of Options
	  	 	3	 
	 (e)
	 	 Exercise of Options
	  	 	3	 
	 (f)
	 	 Payment Upon Exercise
	  	 	3	 
	 6.
	 	 Stock Appreciation Rights
	  	 	4	 
	 (a)
	 	 General
	  	 	4	 
	 (b)
	 	 Measurement Price
	  	 	4	 
	 (c)
	 	 Duration of SARs
	  	 	4	 
	 (d)
	 	 Exercise of SARs
	  	 	5	 
	 7.
	 	 Restricted Stock; Restricted Stock Units
	  	 	5	 
	 (a)
	 	 General
	  	 	5	 
	 (b)
	 	 Terms and Conditions for All Restricted Stock Awards
	  	 	5	 
	 (c)
	 	 Additional Provisions Relating to Restricted Stock
	  	 	5	 
	 (d)
	 	 Additional Provisions Relating to Restricted Stock Units
	  	 	5	 
	 8.
	 	 Other Stock-Based Awards
	  	 	6	 
	 (a)
	 	 General
	  	 	6	 
	 (b)
	 	 Terms and Conditions
	  	 	6	 
	 9.
	 	 Adjustments for Changes in Common Stock and Certain Other Events
	  	 	6	 
	 (a)
	 	 Changes in Capitalization
	  	 	6	 
	 (b)
	 	 Reorganization Events
	  	 	7	 
	 10.
	 	 General Provisions Applicable to Awards
	  	 	9	 
	 (a)
	 	 Transferability of Awards
	  	 	9	 
	 (b)
	 	 Documentation
	  	 	9	 
	 (c)
	 	 Board Discretion
	  	 	9	 
	 (d)
	 	 Termination of Status
	  	 	9	 
	 (e)
	 	 Withholding
	  	 	9	 
	 (f)
	 	 Amendment of Award
	  	 	10	 
	 (g)
	 	 Conditions on Delivery of Stock
	  	 	10	 
	 (h)
	 	 Acceleration
	  	 	10	 
	 11.
	 	 Miscellaneous
	  	 	10	 
	 (a)
	 	 No Right To Employment or Other Status
	  	 	10	 
	 (b)
	 	 No Rights As Stockholder
	  	 	11	 

							
	 (c)
	 	 Effective Date and Term of Plan
	  	 	11	 
	 (d)
	 	 Amendment of Plan
	  	 	11	 
	 (e)
	 	 Authorization of Sub-Plans (including Grants to non-U.S. Employees)
	  	 	11	 
	 (f)
	 	 Compliance with Section 409A of the Code
	  	 	11	 
	 (g)
	 	 Limitations on Liability
	  	 	12	 
	 (h)
	 	 Governing Law
	  	 	12	 

  
 iii 

 2015 STOCK INCENTIVE PLAN 

OF 

DECIBEL THERAPEUTICS, INC. 

 

	1.	 Purpose 

The purpose of this 2015 Stock Incentive Plan (the “Plan”) of Decibel Therapeutics, Inc., a Delaware corporation (the
“Company”), is to advance the interests of the Company’s stockholders by enhancing the Company’s ability to attract, retain and motivate persons who are expected to make important contributions to the Company and by
providing such persons with equity ownership opportunities and performance-based incentives that are intended to better align the interests of such persons with those of the Company’s stockholders. Except where the context otherwise requires,
the term “Company” shall include any of the Company’s present or future parent or subsidiary corporations as defined in Sections 424(e) or (f) of the Internal Revenue Code of 1986, as amended, and any regulations
thereunder (the “Code”) and any other business venture (including, without limitation, joint venture or limited liability company) in which the Company has a controlling interest, as determined by the Board of Directors of the
Company (the “Board”); provided, however, that such other business ventures shall be limited to entities that, where required by Section 409A of the Code, are eligible issuers of service recipient stock (as
defined in Treas. Reg. Section 1.409A-1(b)(5)(iii)(E), or applicable successor regulation). 
  

	2.	 Eligibility 

All of the Company’s employees, officers and directors, as well as consultants and advisors to the Company (as such terms consultants and
advisors are defined and interpreted for purposes of Rule 701 under the Securities Act of 1933, as amended (the “Securities Act”) (or any successor rule)) are eligible to be granted Awards under the Plan. Each person who is granted
an Award under the Plan is deemed a “Participant.” “Award” means Options (as defined in Section 5), SARs (as defined in Section 6), Restricted Stock (as defined in Section 7), Restricted Stock Units
(as defined in Section 7) and Other Stock-Based Awards (as defined in Section 8). 
  

	3.	 Administration and Delegation 

(a) Administration by the Board. The Plan will be administered by the Board. The Board shall have authority to grant Awards and to
adopt, amend and repeal such administrative rules, guidelines and practices relating to the Plan as it shall deem advisable. The Board may construe and interpret the terms of the Plan and any Award agreements entered into under the Plan. The Board
may correct any defect, supply any omission or reconcile any inconsistency in the Plan or any Award in the manner and to the extent it shall deem expedient to carry the Plan into effect and it shall be the sole and final judge of such expediency.
All decisions by the Board shall be made in the Board’s sole discretion and shall be final and binding on all persons having or claiming any interest in the Plan or in any Award. 

(b) Appointment of Committees. To the extent permitted by applicable law, the Board may delegate any or all of its powers under the
Plan to one or more committees or subcommittees of the Board (each, a “Committee”). All references in the Plan to the “Board” shall mean the Board or a Committee of the Board to the extent that the Board’s
powers or authority under the Plan have been delegated to such Committee. 

  
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	4.	 Stock Available for Awards 

(a) Number of Shares. Subject to adjustment under Section 9, Awards may be made under the Plan for up to 20,832,716 shares of
common stock, $0.001 par value per share, of the Company (the “Common Stock”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)). If any Award expires or is terminated,
surrendered or canceled without having been fully exercised, is forfeited in whole or in part (including as the result of shares of Common Stock subject to such Award being repurchased by the Company at the original issuance price pursuant to a
contractual repurchase right), or results in any Common Stock not being issued, the unused Common Stock covered by such Award shall again be available for the grant of Awards under the Plan. Further, shares of Common Stock tendered to the Company by
a Participant to exercise an Award or to satisfy tax withholding obligations arising with respect to an Award shall be added to the number of shares of Common Stock available for the grant of Awards under the Plan. However, in the case of Incentive
Stock Options, the two immediately preceding sentences shall be subject to any limitations under the Code. Shares issued under the Plan may consist in whole or in part of authorized but unissued shares or treasury shares. 

(b) Substitute Awards. In connection with a merger or consolidation of an entity with the Company or the acquisition by the Company of
property or stock of an entity, the Board may grant Awards in substitution for any options or other stock or stock-based awards granted by such entity or an affiliate thereof. Substitute Awards may be granted on such terms as the Board deems
appropriate in the circumstances, notwithstanding any limitations on Awards contained in the Plan. Substitute Awards shall not count against the overall share limit set forth in Section 4(a), except as may be required by reason of
Section 422 and related provisions of the Code. 
  

	5.	 Stock Options 

(a) General. The Board may grant options to purchase Common Stock (each, an “Option”) and determine the number of
shares of Common Stock to be covered by each Option, the exercise price of each Option and the conditions and limitations applicable to the exercise of each Option, including conditions relating to applicable federal or state securities laws, as it
considers necessary or advisable. 
 (b) Incentive Stock Options. An Option that the Board intends to be an “incentive stock
option” as defined in Section 422 of the Code (an “Incentive Stock Option”) shall only be granted to employees of Decibel Therapeutics, Inc., any of Decibel Therapeutics, Inc.’s present or future parent or subsidiary
corporations as defined in Sections 424(e) or (f) of the Code, and any other entities the employees of which are eligible to receive Incentive Stock Options under the Code, and shall be subject to and shall be construed consistently with the
requirements of Section 422 of the Code. An Option that is not intended to be an Incentive Stock Option shall be designated a “Nonstatutory Stock Option.” The Company shall have no liability to a Participant, or any other
party, if an Option (or any part thereof) that is intended to be an Incentive Stock Option is not an Incentive Stock Option or if the Company converts an Incentive Stock Option to a Nonstatutory Stock Option. 

 (c) Exercise Price. The Board shall establish the exercise price of each Option and
specify the exercise price in the applicable Option agreement. The exercise price shall be not less than 100% of the fair market value per share of Common Stock, as determined by (or in a manner approved by) the Board (“Fair Market
Value”), on the date the Option is granted. “Fair Market Value” of a share of Common Stock for purposes of the Plan will be determined as follows: 

(1) if the Common Stock is not publicly traded, the Board will determine the Fair Market Value for purposes of the Plan using any measure of
value it determines to be appropriate (including, as it considers appropriate, relying on appraisals) in a manner consistent with the valuation principles under Code Section 409A, except as the Board may expressly determine otherwise; 

(2) if the Common Stock trades on a national securities exchange, the closing sale price (for the primary trading session) on the date of
grant; or 
 (3) if the Common Stock does not trade on any such exchange, the average of the closing bid and asked prices as reported by an
authorized OTCBB market data vendor as listed on the OTCBB website (otcbb.com) on the date of grant. 
 For any date that is not a trading
day, the Fair Market Value of a share of Common Stock for such date will be determined by using the closing sale price or average of the bid and asked prices, as appropriate, for the immediately preceding trading day and with the timing in the
formulas above adjusted accordingly. The Board can substitute a particular time of day or other measure of “closing sale price” or “bid and asked prices” if appropriate because of exchange or market procedures or can, in its sole
discretion, use weighted averages either on a daily basis or such longer period as complies with Code Section 409A. 
 The Board has
sole discretion to determine the Fair Market Value for purposes of the Plan, and all Awards are conditioned on the participants’ agreement that the Board’s determination is conclusive and binding even though others might make a different
determination. 
 (d) Duration of Options. Each Option shall be exercisable at such times and subject to such terms and conditions as
the Board may specify in the applicable option agreement; provided, however, that no Option will be granted with a term in excess of 10 years. 

(e) Exercise of Options. Options may be exercised by delivery to the Company of a notice of exercise in a form of notice (which may be
electronic) approved by the Company, together with payment in full (in a manner specified in Section 5(f)) of the exercise price for the number of shares for which the Option is exercised. Shares of Common Stock subject to the Option will be
delivered by the Company as soon as practicable following exercise. 
 (f) Payment Upon Exercise. Common Stock purchased upon the
exercise of an Option granted under the Plan shall be paid for as follows: 
 (1) in cash or by check, payable to the order of the Company;

 (2) when the Common Stock is registered under the Securities Exchange Act of 1934, as amended (the “Exchange Act”),
except as may otherwise be provided in the applicable 

  
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Option agreement or approved by the Board, in its sole discretion, by (i) delivery of an irrevocable and unconditional undertaking by a creditworthy broker to deliver promptly to the Company
sufficient funds to pay the exercise price and any required tax withholding or (ii) delivery by the Participant to the Company of a copy of irrevocable and unconditional instructions to a creditworthy broker to deliver promptly to the Company
cash or a check sufficient to pay the exercise price and any required tax withholding; 
 (3) when the Common Stock is registered under the
Exchange Act and to the extent provided for in the applicable Option agreement or approved by the Board, in its sole discretion, by delivery (either by actual delivery or attestation) of shares of Common Stock owned by the Participant valued at
their Fair Market Value, provided (i) such method of payment is then permitted under applicable law, (ii) such Common Stock, if acquired directly from the Company, was owned by the Participant for such minimum period of time, if
any, as may be established by the Board in its discretion and (iii) such Common Stock is not subject to any repurchase, forfeiture, unfulfilled vesting or other similar requirements; 

(4) to the extent provided for in the applicable Nonstatutory Stock Option agreement or approved by the Board in its sole discretion, by
delivery of a notice of “net exercise” to the Company, as a result of which the Participant would pay the exercise price for the portion of the Option being exercised by cancelling a portion of the Option for such number of shares as is
equal to the exercise price divided by the excess of the Fair Market Value on the date of exercise over the Option exercise price per share. 

(5) to the extent permitted by applicable law and provided for in the applicable Option agreement or approved by the Board, in its sole
discretion, by (i) delivery of a promissory note of the Participant to the Company on terms determined by the Board, or (ii) payment of such other lawful consideration as the Board may determine; or 

(6) by any combination of the above permitted forms of payment. 
  

	6.	 Stock Appreciation Rights 

(a) General. The Board may grant Awards consisting of stock appreciation rights (“SARs”) entitling the holder, upon
exercise, to receive an amount of Common Stock or cash or a combination thereof (such form to be determined by the Board) determined by reference to appreciation, from and after the date of grant, in the Fair Market Value of a share of Common Stock
over the measurement price established pursuant to Section 6(b). The date as of which such appreciation is determined shall be the exercise date. 

(b) Measurement Price. The Board shall establish the measurement price of each SAR and specify it in the applicable SAR agreement. The
measurement price shall not be less than 100% of the Fair Market Value on the date the SAR is granted. 
 (c) Duration of SARs. Each
SAR shall be exercisable at such times and subject to such terms and conditions as the Board may specify in the applicable SAR agreement; provided, however, that no SAR will be granted with a term in excess of 10 years. 

 (d) Exercise of SARs. SARs may be exercised by delivery to the Company of a notice of
exercise in a form (which may be electronic) approved by the Company, together with any other documents required by the Board. 
  

	7.	 Restricted Stock; Restricted Stock Units 

(a) General. The Board may grant Awards entitling recipients to acquire shares of Common Stock (“Restricted Stock”),
subject to the right of the Company to repurchase all or part of such shares at their issue price or other stated or formula price (or to require forfeiture of such shares if issued at no cost) from the recipient in the event that conditions
specified by the Board in the applicable Award are not satisfied prior to the end of the applicable restriction period or periods established by the Board for such Award. The Board may also grant Awards entitling the recipient to receive shares of
Common Stock or cash to be delivered at the time such Award vests (“Restricted Stock Units”) (Restricted Stock and Restricted Stock Units are each referred to herein as a “Restricted Stock Award”). 

(b) Terms and Conditions for All Restricted Stock Awards. The Board shall determine the terms and conditions of a Restricted Stock
Award, including the conditions for vesting and repurchase (or forfeiture) and the issue price, if any. 
 (c) Additional Provisions
Relating to Restricted Stock. 
 (1) Dividends. Unless otherwise provided in the applicable Award agreement, any dividends
(whether paid in cash, stock or property) declared and paid by the Company with respect to shares of Restricted Stock (“Accrued Dividends”) shall be paid to the Participant only if and when such shares become free from the
restrictions on transferability and forfeitability that apply to such shares. Each payment of Accrued Dividends will be made no later than the end of the calendar year in which the dividends are paid to stockholders of that class of stock or, if
later, the 15th day of the third month following the lapsing of the restrictions on transferability and the forfeitability provisions applicable to the underlying shares of Restricted Stock. 

(2) Stock Certificates. The Company may require that any stock certificates issued in respect of shares of Restricted Stock, as well as
dividends or distributions paid on such Restricted Stock, shall be deposited in escrow by the Participant, together with a stock power endorsed in blank, with the Company (or its designee). At the expiration of the applicable restriction periods,
the Company (or such designee) shall deliver the certificates no longer subject to such restrictions to the Participant or if the Participant has died, to Participant’s Designated Beneficiary. “Designated Beneficiary” means
(i) the beneficiary designated, in a manner determined by the Board, by a Participant to receive amounts due or exercise rights of the Participant in the event of the Participant’s death or (ii) in the absence of an effective
designation by a Participant, “Designated Beneficiary” means the Participant’s estate. 
 (d) Additional Provisions
Relating to Restricted Stock Units. 
 (1) Settlement. Upon the vesting of and/or lapsing of any other restrictions (i.e.,
settlement) with respect to each Restricted Stock Unit, the Participant shall be entitled to receive from the Company one share of Common Stock or (if so provided in the applicable Award agreement) an amount of cash equal to the Fair Market Value of
one share of Common Stock. The Board may, in its discretion, provide that settlement of Restricted Stock Units shall be deferred, on a mandatory basis or at the election of the Participant in a manner that complies with Section 409A of the
Code. 

  
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 (2) Voting Rights. A Participant shall have no voting rights with respect to any
Restricted Stock Units. 
 (3) Dividend Equivalents. The Award agreement for Restricted Stock Units may provide Participants with the
right to receive an amount equal to any dividends or other distributions declared and paid on an equal number of outstanding shares of Common Stock (“Dividend Equivalents”). Dividend Equivalents may be paid currently or credited to
an account for the Participants, may be settled in cash and/or shares of Common Stock and may be subject to the same restrictions on transfer and forfeitability as the Restricted Stock Units with respect to which paid, in each case to the extent
provided in the applicable Award agreement. 
  

	8.	 Other Stock-Based Awards 

(a) General. Other Awards of shares of Common Stock, and other Awards that are valued in whole or in part by reference to, or are
otherwise based on, shares of Common Stock or other property, may be granted hereunder to Participants (“Other Stock-Based Awards”). Such Other Stock-Based Awards shall also be available as a form of payment in the settlement of
other Awards granted under the Plan or as payment in lieu of compensation to which a Participant is otherwise entitled. Other Stock-Based Awards may be paid in shares of Common Stock or cash, as the Board shall determine. 

(b) Terms and Conditions. Subject to the provisions of the Plan, the Board shall determine the terms and conditions of each Other
Stock-Based Award, including any purchase price applicable thereto. 
  

	9.	 Adjustments for Changes in Common Stock and Certain Other Events 

(a) Changes in Capitalization. In the event of any stock split, reverse stock split, stock dividend, recapitalization, combination of
shares, reclassification of shares, spin-off or other similar change in capitalization or event, or any dividend or distribution to holders of Common Stock other than an ordinary cash dividend, (i) the
number and class of securities available under the Plan, (ii) the number and class of securities and exercise price per share of each outstanding Option, (iii) the share and per-share provisions and
the measurement price of each outstanding SAR, (iv) the number of shares subject to and the repurchase price per share subject to each outstanding Restricted Stock Award and (v) the share and
per-share-related provisions and the purchase price, if any, of each outstanding Other Stock-Based Award, shall be equitably adjusted by the Company (or substituted Awards may be made, if applicable) in the
manner determined by the Board. Without limiting the generality of the foregoing, in the event the Company effects a split of the Common Stock by means of a stock dividend and the exercise price of and the number of shares subject to an outstanding
Option are adjusted as of the date of the distribution of the dividend (rather than as of the record date for such dividend), then an optionee who exercises an Option between the record date and the distribution date for such stock dividend shall be
entitled to receive, on the distribution date, the stock dividend with respect to the shares of Common Stock acquired upon such Option exercise, notwithstanding the fact that such shares were not outstanding as of the close of business on the record
date for such stock dividend. 

 (b) Reorganization Events. 

(1) Definition. A “Reorganization Event” shall mean: (a) any merger or consolidation of the Company with or into
another entity as a result of which all of the Common Stock of the Company is converted into or exchanged for the right to receive cash, securities or other property or is cancelled, (b) any transfer or disposition of all of the Common Stock of
the Company for cash, securities or other property pursuant to a share exchange or other transaction or (c) any liquidation or dissolution of the Company. 

(2) Consequences of a Reorganization Event on Awards Other than Restricted Stock. 

(i) In connection with a Reorganization Event, the Board may take any one or more of the following actions as to all or any (or any portion
of) outstanding Awards other than Restricted Stock on such terms as the Board determines (except to the extent specifically provided otherwise in an applicable Award agreement or another agreement between the Company and the Participant):
(i) provide that such Awards shall be assumed, or substantially equivalent Awards shall be substituted, by the acquiring or succeeding corporation (or an affiliate thereof), (ii) upon written notice to a Participant, provide that all of
the Participant’s unexercised Awards will terminate immediately prior to the consummation of such Reorganization Event unless exercised by the Participant (to the extent then exercisable) within a specified period following the date of such
notice, (iii) provide that outstanding Awards shall become exercisable, realizable, or deliverable, or restrictions applicable to an Award shall lapse, in whole or in part prior to or upon such Reorganization Event, (iv) in the event of a
Reorganization Event under the terms of which holders of Common Stock will receive upon consummation thereof a cash payment for each share surrendered in the Reorganization Event (the “Acquisition Price”), make or provide for a cash
payment to Participants with respect to each Award held by a Participant equal to (A) the number of shares of Common Stock subject to the vested portion of the Award (after giving effect to any acceleration of vesting that occurs upon or
immediately prior to such Reorganization Event) multiplied by (B) the excess, if any, of (I) the Acquisition Price over (II) the exercise, measurement or purchase price of such Award and any applicable tax withholdings, in exchange
for the termination of such Award, (v) provide that, in connection with a liquidation or dissolution of the Company, Awards shall convert into the right to receive liquidation proceeds (if applicable, net of the exercise, measurement or
purchase price thereof and any applicable tax withholdings) and (vi) any combination of the foregoing. In taking any of the actions permitted under this Section 9(b)(2), the Board shall not be obligated by the Plan to treat all Awards, all
Awards held by a Participant, or all Awards of the same type, identically. 
 (ii) Notwithstanding the terms of Section 9(b)(2)(i), in
the case of outstanding Restricted Stock Units that are subject to Section 409A of the Code: (i) if the applicable Restricted Stock Unit agreement provides that the Restricted Stock Units shall be settled upon a “change in control
event” within the meaning of Treasury Regulation Section 1.409A-3(i)(5)(i), and the Reorganization Event constitutes such a “change in control event”, then no assumption or substitution
shall be permitted pursuant to Section 9(b)(2)(i)(i) and the Restricted 

  
 7 

 
Stock Units shall instead be settled in accordance with the terms of the applicable Restricted Stock Unit agreement; and (ii) the Board may only undertake the actions set forth in clauses
(iii), (iv) or (v) of Section 9(b)(2)(i) if the Reorganization Event constitutes a “change in control event” as defined under Treasury Regulation Section 1.409A-3(i)(5)(i) and such
action is permitted or required by Section 409A of the Code; if the Reorganization Event is not a “change in control event” as so defined or such action is not permitted or required by Section 409A of the Code, and the acquiring
or succeeding corporation does not assume or substitute the Restricted Stock Units pursuant to clause (i) of Section 9(b)(2)(i), then the unvested Restricted Stock Units shall terminate immediately prior to the consummation of the
Reorganization Event without any payment in exchange therefor. 
 (iii) For purposes of Section 9(b)(2)(i)(i), an Award (other than
Restricted Stock) shall be considered assumed if, following consummation of the Reorganization Event, such Award confers the right to purchase or receive pursuant to the terms of such Award, for each share of Common Stock subject to the Award
immediately prior to the consummation of the Reorganization Event, the consideration (whether cash, securities or other property) received as a result of the Reorganization Event by holders of Common Stock for each share of Common Stock held
immediately prior to the consummation of the Reorganization Event (and if holders were offered a choice of consideration, the type of consideration chosen by the holders of a majority of the outstanding shares of Common Stock); provided,
however, that if the consideration received as a result of the Reorganization Event is not solely common stock of the acquiring or succeeding corporation (or an affiliate thereof), the Company may, with the consent of the acquiring or succeeding
corporation, provide for the consideration to be received upon the exercise or settlement of the Award to consist solely of such number of shares of common stock of the acquiring or succeeding corporation (or an affiliate thereof) that the Board
determined to be equivalent in value (as of the date of such determination or another date specified by the Board) to the per share consideration received by holders of outstanding shares of Common Stock as a result of the Reorganization Event. 

(3) Consequences of a Reorganization Event on Restricted Stock. Upon the occurrence of a Reorganization Event other than a liquidation
or dissolution of the Company, the repurchase and other rights of the Company with respect to outstanding Restricted Stock shall inure to the benefit of the Company’s successor and shall, unless the Board determines otherwise, apply to the
cash, securities or other property which the Common Stock was converted into or exchanged for pursuant to such Reorganization Event in the same manner and to the same extent as they applied to such Restricted Stock; provided, however,
that the Board may provide for termination or deemed satisfaction of such repurchase or other rights under the instrument evidencing any Restricted Stock or any other agreement between a Participant and the Company, either initially or by amendment.
Upon the occurrence of a Reorganization Event involving the liquidation or dissolution of the Company, except to the extent specifically provided to the contrary in the instrument evidencing any Restricted Stock or any other agreement between a
Participant and the Company, all restrictions and conditions on all Restricted Stock then outstanding shall automatically be deemed terminated or satisfied. 

	10.	 General Provisions Applicable to Awards. 

(a) Transferability of Awards. Awards (or any interest in an Award, including, prior to exercise, any interest in shares of Common
Stock issuable upon exercise of an Option or SAR) shall not be sold, assigned, transferred (including by establishing any short position, put equivalent position (as defined in Rule 16a-1 issued under the
Exchange Act) or call equivalent position (as defined in Rule 16a-1 issued under the Exchange Act)), pledged, hypothecated or otherwise encumbered by the person to whom they are granted, either voluntarily or
by operation of law, and, during the life of the Participant, shall be exercisable only by the Participant; except that Awards, other than Awards subject to Section 409A of the Code, may be transferred to family members (as defined in Rule
701(c)(3) under the Securities Act) through gifts or (other than Incentive Stock Options) domestic relations orders or to an executor or guardian upon the death or disability of the Participant. The Company shall not be required to recognize any
such permitted transfer until such time as such permitted transferee shall deliver to the Company a written instrument, as a condition to such transfer, in form and substance satisfactory to the Company confirming that such transferee shall be bound
by all of the terms and conditions of the Award. References to a Participant, to the extent relevant in the context, shall include references to authorized transferees. For the avoidance of doubt, nothing contained in this Section 10(a) shall
be deemed to restrict a transfer to the Company. 
 (b) Documentation. Each Award shall be evidenced in such form (written,
electronic or otherwise) as the Board shall determine. Each Award may contain terms and conditions in addition to those set forth in the Plan. 

(c) Board Discretion. Except as otherwise provided by the Plan, each Award may be made alone or in addition or in relation to any other
Award. The terms of each Award need not be identical, and the Board need not treat Participants uniformly. 
 (d) Termination of
Status. The Board shall determine the effect on an Award of the disability, death, termination or other cessation of employment, authorized leave of absence or other change in the employment or other status of a Participant and the extent to
which, and the period during which, the Participant, or the Participant’s legal representative, conservator, guardian or Designated Beneficiary, may exercise rights under the Award. 

(e) Withholding. The Participant must satisfy all applicable federal, state, and local or other income and employment tax withholding
obligations before the Company will deliver stock certificates or otherwise recognize ownership of Common Stock under an Award. The Company may decide to satisfy the withholding obligations through additional withholding on salary or wages. If the
Company elects not to or cannot withhold from other compensation, the Participant must pay the Company the full amount, if any, required for withholding or have a broker tender to the Company cash equal to the withholding obligations. Payment of
withholding obligations is due before the Company will issue any shares on exercise, vesting or release from forfeiture of an Award or at the same time as payment of the exercise or purchase price unless the Company determines otherwise. If provided
for in an Award or approved by the Board in its sole discretion, a Participant may satisfy such tax obligations in whole or in part by delivery (either by actual delivery or attestation) of shares of Common Stock, including shares retained from the
Award creating the tax obligation, valued at their Fair Market Value; provided, however, except as 

  
 9 

 
otherwise provided by the Board, that the total tax withholding where stock is being used to satisfy such tax obligations cannot exceed the Company’s minimum statutory withholding
obligations (based on minimum statutory withholding rates for federal and state tax purposes, including payroll taxes, that are applicable to such supplemental taxable income). Shares used to satisfy tax withholding requirements cannot be subject to
any repurchase, forfeiture, unfulfilled vesting or other similar requirements. 
 (f) Amendment of Award. 

(1) The Board may amend, modify or terminate any outstanding Award, including but not limited to, substituting therefor another Award of the
same or a different type, changing the date of exercise or realization, and converting an Incentive Stock Option to a Nonstatutory Stock Option. The Participant’s consent to such action shall be required unless (i) the Board determines
that the action, taking into account any related action, does not materially and adversely affect the Participant’s rights under the Plan or (ii) the change is permitted under Section 9. 

(2) The Board may, without stockholder approval, amend any outstanding Award granted under the Plan to provide an exercise price per share
that is lower than the then-current exercise price per share of such outstanding Award. The Board may also, without stockholder approval, cancel any outstanding award (whether or not granted under the Plan) and grant in substitution therefor new
Awards under the Plan covering the same or a different number of shares of Common Stock and having an exercise price per share lower than the then-current exercise price per share of the cancelled award. 

(g) Conditions on Delivery of Stock. The Company will not be obligated to deliver any shares of Common Stock pursuant to the Plan or to
remove restrictions from shares previously issued or delivered under the Plan until (i) all conditions of the Award have been met or removed to the satisfaction of the Company, (ii) in the opinion of the Company’s counsel, all other
legal matters in connection with the issuance and delivery of such shares have been satisfied, including any applicable securities laws and regulations and any applicable stock exchange or stock market rules and regulations, and (iii) the
Participant has executed and delivered to the Company such representations or agreements as the Company may consider appropriate to satisfy the requirements of any applicable laws, rules or regulations. 

(h) Acceleration. The Board may at any time provide that any Award shall become immediately exercisable in whole or in part, free of
some or all restrictions or conditions, or otherwise realizable in whole or in part, as the case may be. 
  

	11.	 Miscellaneous. 

(a) No Right To Employment or Other Status. No person shall have any claim or right to be granted an Award by virtue of the adoption of
the Plan, and the grant of an Award shall not be construed as giving a Participant the right to continued employment or any other relationship with the Company. The Company expressly reserves the right at any time to dismiss or otherwise terminate
its relationship with a Participant free from any liability or claim under the Plan, except as expressly provided in the applicable Award. 

 (b) No Rights As Stockholder. Subject to the provisions of the applicable Award, no
Participant or Designated Beneficiary shall have any rights as a stockholder with respect to any shares of Common Stock to be distributed with respect to an Award until becoming the record holder of such shares. 

(c) Effective Date and Term of Plan. The Plan shall become effective on the date on which it is adopted by the Board. No Awards shall
be granted under the Plan after the expiration of 10 years from the earlier of (i) the date on which the Plan was adopted by the Board or (ii) the date the Plan was approved by the Company’s stockholders, but Awards previously granted
may extend beyond that date. 
 (d) Amendment of Plan. The Board may amend, suspend or terminate the Plan or any portion thereof at
any time; provided that if at any time the approval of the Company’s stockholders is required as to any modification or amendment under Section 422 of the Code or any successor provision with respect to Incentive Stock Options, the
Board may not effect such modification or amendment without such approval. Unless otherwise specified in the amendment, any amendment to the Plan adopted in accordance with this Section 11(d) shall apply to, and be binding on the holders of,
all Awards outstanding under the Plan at the time the amendment is adopted, provided the Board determines that such amendment, taking into account any related action, does not materially and adversely affect the rights of Participants under the
Plan. 
 (e) Authorization of Sub-Plans (including Grants to
non-U.S. Employees). The Board may from time to time establish one or more sub-plans under the Plan for purposes of satisfying applicable securities, tax or other
laws of various jurisdictions. The Board shall establish such sub-plans by adopting supplements to the Plan containing (i) such limitations on the Board’s discretion under the Plan as the Board deems
necessary or desirable or (ii) such additional terms and conditions not otherwise inconsistent with the Plan as the Board shall deem necessary or desirable. All supplements adopted by the Board shall be deemed to be part of the Plan, but each
supplement shall apply only to Participants within the affected jurisdiction and the Company shall not be required to provide copies of any supplement to Participants in any jurisdiction which is not the subject of such supplement. 

(f) Compliance with Section 409A of the Code. Except as provided in individual Award agreements initially or by
amendment, if and to the extent (i) any portion of any payment, compensation or other benefit provided to a Participant pursuant to the Plan in connection with Participant’s employment termination constitutes “nonqualified deferred
compensation” within the meaning of Section 409A of the Code and (ii) the Participant is a specified employee as defined in Section 409A(a)(2)(B)(i) of the Code, in each case as determined by the Company in accordance with its
procedures, by which determinations the Participant (through accepting the Award) agrees that the Participant is bound, such portion of the payment, compensation or other benefit shall not be paid before the day that is six months plus one
day after the date of “separation from service” (as determined under Section 409A of the Code) (the “New Payment Date”), except as Section 409A of the Code may then permit. The aggregate of any payments that
otherwise would have been paid to the Participant during the period between the date of separation from service and the New Payment Date shall be paid to the Participant in a lump sum on such New Payment Date, and any remaining payments will be paid
on their original schedule. 

  
 11 

 The Company makes no representations or warranty and shall have no liability to the Participant or any other
person if any provisions of or payments, compensation or other benefits under the Plan are determined to constitute nonqualified deferred compensation subject to Section 409A of the Code but do not to satisfy the conditions of that section.

 (g) Limitations on Liability. Notwithstanding any other provisions of the Plan, no individual acting as a director,
officer, other employee, or agent of the Company will be liable to any Participant, former Participant, spouse, beneficiary, or any other person for any claim, loss, liability, or expense incurred in connection with the Plan, nor will such
individual be personally liable with respect to the Plan because of any contract or other instrument such individual executes in such individual’s capacity as a director, officer, other employee, or agent of the Company. The Company will
indemnify and hold harmless each director, officer, other employee, or agent of the Company to whom any duty or power relating to the administration or interpretation of the Plan has been or will be delegated, against any cost or expense (including
attorneys’ fees) or liability (including any sum paid in settlement of a claim with the Board’s approval) arising out of any act or omission to act concerning the Plan unless arising out of such person’s own fraud or bad faith. 

(h) Governing Law. The provisions of the Plan and all Awards made hereunder shall be governed by and interpreted in accordance with the
laws of the State of Delaware, excluding choice-of-law principles of the law of such state that would require the application of the laws of a jurisdiction other than
the State of Delaware. 
 * * * * 

 DECIBEL THERAPEUTICS, INC. 

2015 STOCK INCENTIVE PLAN 

CALIFORNIA SUPPLEMENT 

Pursuant to Section 11(e) of the Plan, the Board has adopted this supplement for purposes of satisfying the requirements of
Section 25102(o) of the California Law: 
 Any Awards granted under the Plan to a Participant who is a resident of the State of
California on the date of grant (a “California Participant”) shall be subject to the following additional limitations, terms and conditions: 

1. Additional Limitations on Options. 

(a) Maximum Duration of Options. No Options granted to California Participants shall have a term in excess of 10 years measured from
the Option grant date. 
 (b) Minimum Exercise Period Following Termination. Unless a California Participant’s employment is
terminated for cause (as defined by applicable law, the terms of the Plan or option grant or a contract of employment), in the event of termination of employment of such Participant, such Participant shall have the right to exercise an Option, to
the extent that such Participant is entitled to exercise such Option on the date employment terminated, until the earlier of: (i) at least six months from the date of termination, if termination was caused by such Participant’s death or
disability, (ii) at least 30 days from the date of termination, if termination was caused other than by such Participant’s death or disability and (iii) the Option expiration date. 

2. Additional Limitations for Other Stock-Based Awards. The terms of all Awards granted to a California Participant under Section 8 of the Plan
shall comply, to the extent applicable, with Sections 260.140.42, 260.140.45 and 260.140.46 of the California Code of Regulations. 
 3. Additional
Limitations on Timing of Awards. No Award granted to a California Participant shall become exercisable, vested or realizable, as applicable to such Award, unless the Plan has been approved by the holders of a majority of the Company’s
outstanding voting securities by the later of (i) within 12 months before or after the date the Plan was adopted by the Board, or (ii) prior to or within 12 months of the granting of any Award to a California Participant. 

4. Additional Restriction Regarding Recapitalizations, Stock Splits, Etc. For purposes of Section 9 of the Plan, in the event of a stock split,
reverse stock split, stock dividend, recapitalization, combination, reclassification or other distribution of the Company’s securities underlying the Award without the receipt of consideration by the Company, the number of securities
purchasable, and in the case of Options, the exercise price of such Options, must be proportionately adjusted. 
 5. Additional Limitations on
Transferability of Awards. Notwithstanding the provisions of Section 10(a) of the Plan, an Award granted to a California Participant may not be transferred to an executor or guardian upon the disability of the Participant. 

* * * * 

  
 13EX-10.3

 Exhibit 10.3 

[NOTE: UNLESS THE SHARES ARE FULLY VESTED UPON GRANT, IT IS 

GENERALLY ADVISABLE FOR THE PARTICIPANT TO FILE 83(B) ELECTION.] 

DECIBEL THERAPEUTICS, INC. 

RESTRICTED STOCK AGREEMENT 

GRANTED UNDER 2015 STOCK INCENTIVE PLAN 

This Restricted Stock Agreement (the “Agreement”) is made this [____] day of [_____________], 20[ ], between Decibel
Therapeutics, Inc., a Delaware corporation (the “Company”), and [________________________] (the “Participant”). 

For valuable consideration, receipt of which is acknowledged, the parties hereto agree as follows: 

 

	 	1.	 Purchase of Shares. 

The Company shall issue and sell to the Participant, and the Participant shall purchase from the Company, subject to the terms and conditions
set forth in this Agreement and in the Company’s 2015 Stock Incentive Plan (the “Plan”), [______] shares (the “Shares”) of common stock, $0.001 par value, of the Company (“Common Stock”), at a
purchase price of $[_____] per share. The aggregate purchase price for the Shares shall be paid by the Participant by check payable to the order of the Company or such other method as may be acceptable to the Company. Upon receipt by the
Company of payment for the Shares, the Company shall issue to the Participant one or more certificates in the name of the Participant for that number of Shares purchased by the Participant. The Participant agrees that the Shares shall be subject to
the purchase options set forth in Sections 3 and 6 of this Agreement and the restrictions on transfer set forth in Section 5 of this Agreement. 
  

	 	2.	 Certain Definitions. 

(a)     “Change in Control” shall mean the sale of all or substantially all of the outstanding shares of
capital stock, assets or business of the Company, by merger, consolidation, sale of assets or otherwise (other than a merger or consolidation in which all or substantially all of the individuals and entities who were beneficial owners of the
Company’s voting securities immediately prior to such transaction beneficially own, directly or indirectly, more than 75% (determined on an as-converted basis) of the outstanding securities entitled to
vote generally in the election of directors of the resulting, surviving or acquiring corporation in such transaction). 

(b)     “Service” shall mean employment by or the provision of services to the Company or a parent or
subsidiary thereof as an advisor, officer, consultant or member of the Board of Directors. 
 (c)    “Vesting
Commencement Date” shall mean [_________________]. 
  

	 	3.	 Purchase Option. 

(a)    In the event that the Participant ceases to provide Service for any reason or no reason, prior to the fourth (4th) anniversary of the Vesting Commencement Date, the Company shall have the right and option (the “Purchase Option”) to purchase from the Participant, for a sum of $0.001 per share
(the “Option Price”), some or all of the Shares as set forth herein. 

 (b)    All of the Shares shall initially be subject to the Purchase
Option. The Participant shall acquire a vested interest in, and the Company’s Purchase Option shall accordingly lapse with respect to, (i) twenty-five percent (25%) of the Shares upon Participant’s completion of one (1) year of
Service measured from the Vesting Commencement Date and (ii) the balance of the Shares in a series of successive equal monthly installments of 1/48 of the Shares upon Recipient’s completion of each additional month of Service over the thirty-six (36)-month period measured from the first anniversary of the Vesting Commencement Date. 
  

	 	4.	 Exercise of Purchase Option and Closing. 

(a)    The Company may exercise the Purchase Option by delivering or mailing to the Participant (or the Participant’s
estate), within 180 days after the termination of the Service of the Participant, a written notice of exercise of the Purchase Option. Such notice shall specify the number of Shares to be purchased. If and to the extent the Purchase Option is not so
exercised by the giving of such a notice within such 180-day period, the Purchase Option shall automatically expire and terminate effective upon the expiration of such
180-day period. 
 (b)    Within ten (10) days after delivery to the
Participant of the Company’s notice of the exercise of the Purchase Option pursuant to subsection (a) above, the Participant (or the Participant’s estate) shall, pursuant to the provisions of the Joint Escrow Instructions referred to
in Section 8 below, tender to the Company at its principal offices the certificate or certificates representing the Shares that the Company has elected to purchase in accordance with the terms of this Agreement, duly endorsed in blank or with
duly endorsed stock powers attached thereto, all in form suitable for the transfer of such Shares to the Company. Promptly following its receipt of such certificate or certificates, the Company shall pay to the Participant the aggregate Option Price
for such Shares (provided that any delay in making such payment shall not invalidate the Company’s exercise of the Purchase Option with respect to such Shares). 

(c)    After the time at which any Shares are required to be delivered to the Company for transfer to the Company pursuant
to subsection (b) above, the Company shall not pay any dividend to the Participant on account of such Shares or permit the Participant to exercise any of the privileges or rights of a stockholder with respect to such Shares, but shall, in so
far as permitted by law, treat the Company as the owner of such Shares. 
 (d)    The Option Price may be payable, at
the option of the Company, in cancellation of all or a portion of any outstanding indebtedness of the Participant to the Company or in cash (by check) or both. 

(e)    The Company shall not purchase any fraction of a Share upon exercise of the Purchase Option, and any fraction of a
Share resulting from a computation made pursuant to Section 3 of this Agreement shall be rounded to the nearest whole Share (with any one-half Share being rounded upward). 

  
 -2- 

 (f)    The Company may assign its Purchase Option to one or more persons
or entities. 
  

	 	5.	 Restrictions on Transfer. 

(a)    The Participant shall not sell, assign, transfer, pledge, hypothecate or otherwise dispose of, by operation of law
or otherwise (collectively “transfer”) any Shares, or any interest therein, that are subject to the Purchase Option, except that the Participant may transfer such Shares (i) to or for the benefit of any spouse, children,
parents, uncles, aunts, siblings, grandchildren and any other relatives approved by the Board of Directors (collectively, “Approved Relatives”) or to a trust established solely for the benefit of the Participant and/or Approved
Relatives, provided that such Shares shall remain subject to this Agreement (including without limitation the restrictions on transfer set forth in this Section 5, the Purchase Option and the right of first refusal set forth in
Section 6) and such permitted transferee shall, as a condition to such transfer, deliver to the Company a written instrument confirming that such transferee shall be bound by all of the terms and conditions of this Agreement or (ii) as
part of the sale of all or substantially all of the shares of capital stock of the Company (including pursuant to a merger or consolidation), provided that, in accordance with the Plan, the securities or other property received by the
Participant in connection with such transaction shall remain subject to this Agreement. 
 (b)    The Participant shall
not transfer any Shares, or any interest therein, that are no longer subject to the Purchase Option, except in accordance with Section 6 below. 
  

	 	6.	 Right of First Refusal. 

(a)    If the Participant proposes to transfer any Shares that are no longer subject to the Purchase Option (either because
they are free from the Purchase Option pursuant to Section 3 or because the Purchase Option expired unexercised pursuant to Section 4), then the Participant shall first give written notice of the proposed transfer (the “Transfer
Notice”) to the Company. The Transfer Notice shall name the proposed transferee and state the number of such Shares the Participant proposes to transfer (the “Offered Shares”), the price per share and all other material
terms and conditions of the transfer. 
 (b)    For 30 days following its receipt of such Transfer Notice, the Company
shall have the option to purchase all or part of the Offered Shares at the price and upon the terms set forth in the Transfer Notice. In the event the Company elects to purchase all or part of the Offered Shares, it shall give written notice of such
election to the Participant within such 30-day period. Within 10 days after the Participant’s receipt of such notice, the Participant shall tender to the Company at its principal offices the certificate
or certificates representing the Offered Shares to be purchased by the Company, duly endorsed in blank by the Participant or with duly endorsed stock powers attached thereto, all in a form suitable for transfer of the Offered Shares to the Company.
Promptly following receipt of such certificate or certificates, the Company shall deliver or mail to the Participant a check in payment of the purchase price for such Offered Shares; provided that if the terms of payment set forth in
the Transfer Notice were other than cash against delivery, the Company may pay for the Offered Shares on the same terms and conditions as were set forth in the Transfer Notice; and provided further that any delay in making such payment
shall not invalidate the Company’s exercise of its option to purchase the Offered Shares. 

  
 -3- 

 (c)    If the Company does not elect to acquire all of the Offered
Shares, the Participant may, within the 30-day period following the expiration of the option granted to the Company under subsection (b) above, transfer the Offered Shares which the Company has not
elected to acquire to the proposed transferee, provided that such transfer shall not be on terms and conditions more favorable to the transferee than those contained in the Transfer Notice. Notwithstanding any of the above, all Offered
Shares transferred pursuant to this Section 6 shall remain subject to this Agreement (including without limitation the restrictions on transfer set forth in Section 5 and the right of first refusal set forth in this Section 6) and
such transferee shall, as a condition to such transfer, deliver to the Company a written instrument confirming that such transferee shall be bound by all of the terms and conditions of this Agreement. 

(d)    After the time at which the Offered Shares are required to be delivered to the Company for transfer to the Company
pursuant to subsection (b) above, the Company shall not pay any dividend to the Participant on account of such Offered Shares or permit the Participant to exercise any of the privileges or rights of a stockholder with respect to such Offered
Shares, but shall, insofar as permitted by law, treat the Company as the owner of such Offered Shares. 
 (e)    The
following transactions shall be exempt from the provisions of this Section 6: 
 (1)    a transfer of Shares to or
for the benefit of any Approved Relatives, or to a trust established solely for the benefit of the Participant and/or Approved Relatives; 

(2)    any transfer pursuant to an effective registration statement filed by the Company under the Securities Act of
1933, as amended (the “Securities Act”); and 
 (3)    the sale of all or substantially all of the
outstanding shares of capital stock of the Company (including pursuant to a merger or consolidation); 
 provided, however, that in the case of a
transfer pursuant to clause (1) above, such Shares shall remain subject to this Agreement (including without limitation the restrictions on transfer set forth in Section 5 and the right of first refusal set forth in this Section 6)
and such transferee shall, as a condition to such transfer, deliver to the Company a written instrument confirming that such transferee shall be bound by all of the terms and conditions of this Agreement. 

(f)    The Company may assign its rights to purchase Offered Shares in any particular transaction under this
Section 6 to one or more persons or entities. 

  
 -4- 

 (g)    The provisions of this Section 6 shall terminate upon the
earlier of the following events: 
 (1)    the closing of the sale of shares of Common Stock in an underwritten public
offering pursuant to an effective registration statement filed by the Company under the Securities Act; or 
 (2)    a
Change in Control. 
 (h)    The Company shall not be required (1) to transfer on its books any of the Shares which
shall have been sold or transferred in violation of any of the provisions set forth in this Agreement, or (2) to treat as owner of such Shares or to pay dividends to any transferee to whom any such Shares shall have been so sold or transferred.

  

	 	7.	 Agreement in Connection with Initial Public Offering. 

The Participant agrees, in connection with the initial underwritten public offering of the Common Stock pursuant to a registration statement
under the Securities Act, (i) not to (a) offer, pledge, announce the intention to sell, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to
purchase, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for shares of Common Stock or (b) enter into any swap or other agreement that
transfers, in whole or in part, any of the economic consequences of ownership of shares of Common Stock, whether any transaction described in clause (a) or (b) is to be settled by delivery of shares of Common Stock or other securities, in cash
or otherwise, during the period beginning on the date of the filing of such registration statement with the Securities and Exchange Commission and ending 180 days from the date of the final prospectus relating to the offering (plus up to an
additional 34 days to the extent requested by the managing underwriters for such offering in order to address NASD Rule 2711(f)(4) or NYSE Rule 472(f)(4) or any similar successor provision), and (ii) to execute any agreement reflecting clause
(i) above as may be requested by the Company or the managing underwriters at the time of such offering. The Company may impose stop-transfer instructions with respect to the shares of Common Stock or other securities subject to the foregoing
restriction until the end of the “lock-up” period. 
  

	 	8.	 Escrow. 

The Participant shall, upon the execution of this Agreement, execute Joint Escrow Instructions in the form attached to this Agreement as
Exhibit A. The Joint Escrow Instructions shall be delivered to the Secretary of the Company, as escrow agent thereunder. The Participant shall deliver to such escrow agent a stock assignment duly endorsed in blank, in the form attached to
this Agreement as Exhibit B, and hereby instructs the Company to deliver to such escrow agent, on behalf of the Participant, the certificate(s) evidencing the Shares issued hereunder. Such materials shall be held by such escrow agent pursuant
to the terms of such Joint Escrow Instructions. 

  
 -5- 

	 	9.	 Restrictive Legends. 

All certificates representing Shares shall have affixed thereto legends in substantially the following form, in addition to any other legends
that may be required under federal or state securities laws: 
 “The shares of stock represented by this certificate are subject to
restrictions on transfer and an option to purchase set forth in a certain Restricted Stock Agreement between the corporation and the registered owner of these shares (or such owner’s predecessor in interest), and such Agreement is available for
inspection without charge at the office of the Secretary of the corporation.” 
 “The shares represented by this certificate have
not been registered under the Securities Act of 1933, as amended, and may not be sold, transferred or otherwise disposed of in the absence of an effective registration statement under such Act or an opinion of counsel satisfactory to the corporation
to the effect that such registration is not required.” 
  

	 	10.	 Provisions of the Plan. 

This Agreement is subject to the provisions of the Plan, a copy of which is furnished to the Participant with this Agreement. 

 

	 	11.	 Investment Representations. 

The Participant represents, warrants and covenants as follows: 

(a)    The Participant is purchasing the Shares for Participant’s own account for investment only, and not with a
view to, or for sale in connection with, any distribution of the Shares in violation of the Securities Act, or any rule or regulation under the Securities Act. 

(b)    The Participant has had such opportunity as Participant has deemed adequate to obtain from representatives of the
Company such information as is necessary to permit him to evaluate the merits and risks of Participant’s investment in the Company. 

(c)    The Participant has sufficient experience in business, financial and investment matters to be able to evaluate the
risks involved in the purchase of the Shares and to make an informed investment decision with respect to such purchase. 

(d)    The Participant can afford a complete loss of the value of the Shares and is able to bear the economic risk of
holding such Shares for an indefinite period. 
 (e) The Participant understands that (i) the Shares have not been registered under the
Securities Act and are “restricted securities” within the meaning of Rule 144 under the Securities Act; (ii) the Shares cannot be sold, transferred or otherwise disposed of unless they are subsequently registered under the Securities Act
or an exemption from registration is then available; (iii) in any event, the exemption from registration under Rule 144 will not be available 

  
 -6- 

 
for at least one year and even then will not be available unless a public market then exists for the Common Stock, adequate information concerning the Company is then available to the public, and
other terms and conditions of Rule 144 are complied with; and (iv) there is now no registration statement on file with the Securities and Exchange Commission with respect to any stock of the Company and the Company has no obligation or
current intention to register the Shares under the Securities Act. 
  

	 	12.	 Withholding Taxes; Section 83(b) Election. 

(a)    The Participant acknowledges and agrees that the Company has the right to deduct from payments of any kind otherwise
due to the Participant any federal, state or local taxes of any kind required by law to be withheld with respect to the purchase of the Shares by the Participant or the lapse of the Purchase Option. 

(b)    The Participant has reviewed with the Participant’s own tax advisors the federal, state, local and foreign tax
consequences of this investment and the transactions contemplated by this Agreement. The Participant is relying solely on such advisors and not on any statements or representations of the Company or any of its agents. The Participant understands
that the Participant (and not the Company) shall be responsible for the Participant’s own tax liability that may arise as a result of this investment or the transactions contemplated by this Agreement. The Participant understands that it may be
beneficial in many circumstances to elect to be taxed at the time the Shares are granted by the Company rather than when and as the Company’s Purchase Option expires by filing an election under Section 83(b) of the Internal Revenue Code of
1986 with the I.R.S. within 30 days from the date of grant by the Company. 
 THE PARTICIPANT ACKNOWLEDGES THAT IT IS SOLELY THE
PARTICIPANT’S RESPONSIBILITY AND NOT THE COMPANY’S TO FILE TIMELY THE ELECTION UNDER SECTION 83(b), EVEN IF THE PARTICIPANT REQUESTS THE COMPANY OR ITS REPRESENTATIVES TO MAKE THIS FILING ON THE PARTICIPANT’S BEHALF. 

 

	 	13.	 Miscellaneous. 

(a)    No Rights to Employment. The Participant acknowledges and agrees that the vesting of the Shares pursuant to
Section 3 hereof is earned only by the Participant’s continuous Service (not through the act of being hired or purchasing the Shares hereunder). The Participant further acknowledges and agrees that the transactions contemplated hereunder
and the vesting schedule set forth herein do not constitute an express or implied promise of continued engagement as an employee or consultant for the vesting period, for any period, or at all. 

(b)    Severability. The invalidity or unenforceability of any provision of this Agreement shall not affect the
validity or enforceability of any other provision of this Agreement, and each other provision of this Agreement shall be severable and enforceable to the extent permitted by law. 

  
 -7- 

 (c)    Waiver. Any provision for the benefit of the Company
contained in this Agreement may be waived, either generally or in any particular instance, by the Board of Directors of the Company. 

(d)    Binding Effect. This Agreement shall be binding upon and inure to the benefit of the Company and the
Participant and their respective heirs, executors, administrators, legal representatives, successors and assigns, subject to the restrictions on transfer set forth in Sections 5 and 6 of this Agreement. 

(e)    Notice. All notices required or permitted hereunder shall be in writing and deemed effectively given upon
personal delivery or five days after deposit in the United States Post Office, by registered or certified mail, postage prepaid, addressed to the other party hereto at the address shown beneath his or her or its respective signature to this
Agreement, or at such other address or addresses as either party shall designate to the other in accordance with this Section 13(e). 

(f)    Pronouns. Whenever the context may require, any pronouns used in this Agreement shall include the
corresponding masculine, feminine or neuter forms, and the singular form of nouns and pronouns shall include the plural, and vice versa. 

(g)    Entire Agreement. This Agreement and the Plan constitute the entire agreement between the parties, and
supersedes all prior agreements and understandings, relating to the subject matter of this Agreement. 

(h)    Amendment. This Agreement may be amended or modified only by a written instrument executed by both the
Company and the Participant. 
 (i)    Governing Law. This Agreement shall be construed, interpreted and enforced
in accordance with the internal laws of the State of Delaware without regard to any applicable conflict of law principles. 

(j)    Participant’s Acknowledgments. The Participant acknowledges that he or she: (i) has read this
Agreement; (ii) has been represented in the preparation, negotiation, and execution of this Agreement by legal counsel of the Participant’s own choice or has voluntarily declined to seek such counsel; (iii) understands the terms and
consequences of this Agreement; (iv) is fully aware of the legal and binding effect of this Agreement; and (v) understands that the law firm of WilmerHale is acting as counsel to the Company in connection with the transactions contemplated
by the Agreement, and is not acting as counsel for the Participant. 
 [Remainder of Page Intentionally Left Blank] 

  
 -8- 

 IN WITNESS WHEREOF, the parties hereto have executed the Restricted Stock Agreement as of
the date and year first above written. The Participant hereby agrees to the terms and conditions thereof. The Participant hereby acknowledges receipt of a copy of the Company’s 2015 Stock Incentive Plan. 

 

			
	 COMPANY:
  

DECIBEL THERAPEUTICS, INC.

		
	 By:
	 	 
		 	Name:                                     
                                         
   
		 	Title:                                    
                                         
      

  

			
	Address:	 	 1325 Boylston Street

Suite 500
 Boston, MA
02115

  

			
	PARTICIPANT:
		
	 By:
	 	 
		 	Name:                                     
                                         
   

  

			
	Address:	 	  [                                   
                                         
  ]
		 	  [                                   
                                         
  ]

  

			
	SPOUSAL CONSENT:
		
	 By:
	 	 
		 	Name:                                     
                                         
   

  

			
	Address:	 	  [                                   
                                         
  ]
		 	  [                                   
                                         
  ]

  
 SIGNATURE PAGE TO
RESTRICTED STOCK AGREEMENT 
 GRANTED UNDER STOCK INCENTIVE PLAN 

 EXHIBIT A 

JOINT ESCROW INSTRUCTIONS 

  
 -10- 

 DECIBEL THERAPEUTICS, INC. 

JOINT ESCROW INSTRUCTIONS 

[___________, 20__] 
 Decibel Therapeutics, Inc.

 1325 Boylston Street 
 Suite 500 

Boston, MA 02115 
 Attention: Secretary 

Dear Secretary: 
 As Escrow Agent for Decibel
Therapeutics, Inc., a Delaware corporation (the “Company”), and its successors in interest under the Restricted Stock Agreement (the “Agreement”) of even date herewith, to which a copy of these Joint Escrow
Instructions is attached, and the undersigned person (“Holder”), you are hereby authorized and directed to hold the documents delivered to you pursuant to the terms of the Agreement in accordance with the following instructions:

 1.    Appointment. Holder irrevocably authorizes the Company to deposit with you any certificates evidencing
Shares (as defined in the Agreement) to be held by you hereunder and any additions and substitutions to said Shares. For purposes of these Joint Escrow Instructions, “Shares” shall be deemed to include any additional or substitute
property. Holder does hereby irrevocably constitute and appoint you as his or her attorney-in-fact and agent for the term of this escrow to execute with respect to such
Shares all documents necessary or appropriate to make such Shares negotiable and to complete any transaction herein contemplated. Subject to the provisions of this Section 1 and the terms of the Agreement, Holder shall exercise all rights and
privileges of a stockholder of the Company while the Shares are held by you. 
 2.     Closing of Purchase. 

(a)    Upon any purchase by the Company of the Shares pursuant to the Agreement, the Company shall give to Holder and you a
written notice specifying the number of Shares to be purchased, the purchase price for the Shares, as determined pursuant to the Agreement, and the time for a closing hereunder (the “Closing”) at the principal office of the Company.
Holder and the Company hereby irrevocably authorize and direct you to close the transaction contemplated by such notice in accordance with the terms of said notice. 

(b)    At the Closing, you are directed (i) to date the stock assignment form or forms necessary for the transfer of
the Shares, (ii) to fill in on such form or forms the number of Shares being transferred, and (iii) to deliver the same, together with the certificate or certificates evidencing the Shares to be transferred, to the Company against the
simultaneous delivery to you of the purchase price for the Shares being purchased pursuant to the Agreement. 

 3.    Withdrawal. The Holder shall have the right to withdraw
from this escrow any Shares as to which the Purchase Option (as defined in the Agreement) has terminated or expired. 

4.    Duties of Escrow Agent. 

(a)    Your duties hereunder may be altered, amended, modified or revoked only by a writing signed by all of the parties
hereto. 
 (b)    You shall be obligated only for the performance of such duties as are specifically set forth herein
and may rely and shall be protected in relying or refraining from acting on any instrument reasonably believed by you to be genuine and to have been signed or presented by the proper party or parties. You shall not be personally liable for any act
you may do or omit to do hereunder as Escrow Agent or as attorney-in-fact of Holder while acting in good faith and in the exercise of your own good judgment, and any act
done or omitted by you pursuant to the advice of your own attorneys shall be conclusive evidence of such good faith. 

(c)    You are hereby expressly authorized to disregard any and all warnings given by any of the parties hereto or by any
other person or entity, excepting only orders or process of courts of law, and are hereby expressly authorized to comply with and obey orders, judgments or decrees of any court. If you are uncertain of any actions to be taken or instructions to be
followed, you may refuse to act in the absence of an order, judgment or decrees of a court. In case you obey or comply with any such order, judgment or decree of any court, you shall not be liable to any of the parties hereto or to any other person
or entity, by reason of such compliance, notwithstanding any such order, judgment or decree being subsequently reversed, modified, annulled, set aside, vacated or found to have been entered without jurisdiction. 

(d)    You shall not be liable in any respect on account of the identity, authority or rights of the parties executing or
delivering or purporting to execute or deliver the Agreement or any documents or papers deposited or called for hereunder. 

(e)    You shall be entitled to employ such legal counsel and other experts as you may deem necessary properly to advise
you in connection with your obligations hereunder and may rely upon the advice of such counsel. 
 (f)    Your rights
and responsibilities as Escrow Agent hereunder shall terminate if (i) you cease to be Secretary of the Company or (ii) you resign by written notice to each party. In the event of a termination under clause (i), your successor as
Secretary shall become Escrow Agent hereunder; in the event of a termination under clause (ii), the Company shall appoint a successor Escrow Agent hereunder. 

(g)    If you reasonably require other or further instruments in connection with these Joint Escrow Instructions or
obligations in respect hereto, the necessary parties hereto shall join in furnishing such instruments. 
 (h)    It is
understood and agreed that if you believe a dispute has arisen with respect to the delivery and/or ownership or right of possession of the securities held by you hereunder, you are authorized and directed to retain in your possession without
liability to anyone all or any part of said securities until such dispute shall have been settled either by mutual written agreement of the parties concerned or by a final order, decree or judgment of a court of competent jurisdiction after the time
for appeal has expired and no appeal has been perfected, but you shall be under no duty whatsoever to institute or defend any such proceedings. 

 (i)    These Joint Escrow Instructions set forth your sole duties with
respect to any and all matters pertinent hereto and no implied duties or obligations shall be read into these Joint Escrow Instructions against you. 

(j)    The Company shall indemnify you and hold you harmless against any and all damages, losses, liabilities, costs, and
expenses, including attorneys’ fees and disbursements, (including without limitation the fees of counsel retained pursuant to Section 4(e) above, for anything done or omitted to be done by you as Escrow Agent in connection with this
Agreement or the performance of your duties hereunder, except such as shall result from your gross negligence or willful misconduct. 

5.    Notice. Any notice required or permitted hereunder shall be given in writing and shall be deemed effectively
given upon personal delivery or upon deposit in the United States Post Office, by registered or certified mail with postage and fees prepaid, addressed to each of the other parties thereunto entitled at the following addresses, or at such other
addresses as a party may designate by ten days’ advance written notice to each of the other parties hereto. 
  

			
	COMPANY:	  	Notices to the Company shall be sent to the address set forth in the salutation hereto, Attn: President
		
	HOLDER:	  	Notices to Holder shall be sent to the address set forth below Holder’s signature below.
		
	ESCROW AGENT:	  	Notices to the Escrow Agent shall be sent to the address set forth in the salutation hereto.

 6.    Miscellaneous. 

(a)    By signing these Joint Escrow Instructions, you become a party hereto only for the purpose of said Joint Escrow
Instructions, and you do not become a party to the Agreement. 
 (b)    This instrument shall be binding upon and inure
to the benefit of the parties hereto and their respective successors and permitted assigns. 
 [Remainder of Page Intentionally Left Blank]

 IN WITNESS WHEREOF, the parties hereto have executed these Joint Escrow Instructions as of
the day and year first above written. 
  

			
	 Very truly yours,
  

COMPANY:
  

DECIBEL THERAPEUTICS, INC.

		
	 By:
	 	 
		 	Name:                                     
                                         
   
		 	Title:                                    
                                         
      

  

			
	HOLDER:
		
	 By:
	 	 
		 	Name:                                     
                                         
   

  

			
	Address:	 	  [                                   
                                         
  ]
		 	  [                                   
                                         
  ]

  

			
	ESCROW AGENT:
		
	 By:
	 	 
		 	Name:                                     
                                         
   
		 	Title:   Secretary

  
 SIGNATURE PAGE TO
JOINT ESCROW INSTRUCTIONS 

 EXHIBIT B 

STOCK ASSIGNMENT SEPARATE FROM CERTIFICATE 

 STOCK ASSIGNMENT SEPARATE FROM
CERTIFICATE 
 FOR VALUE RECEIVED, I hereby sell, assign and transfer unto ____________________________________
(_________) shares of Common Stock, $0.001 par value per share, of Decibel Therapeutics, Inc. (the “Corporation”) standing in my name on the books of the Corporation represented by Certificate(s) Number __________ herewith, and do
hereby irrevocably constitute and appoint Wilmer Cutler Pickering Hale and Dorr LLP attorney to transfer the said stock on the books of the Corporation with full power of substitution in the premises. 

 

			
	Dated:	 	 

  

	
	PARTICIPANT:
	
	   

	[Name]
	
	   

	Name of Spouse (if any):

 Instructions to Participant: Please do not fill in any blanks other than the signature line(s). The
purpose of the Stock Assignment Separate from Certificate is to enable the Company to acquire the Shares upon exercise of its Right of First Refusal and/or Purchase Option without requiring additional signatures on the part of the Participant or
Participant’s spouse, if any. The signature(s) to this assignment must correspond with the name as written upon the face of the certificate, in every particular, without alteration, enlargement, or any change whatever. 

 NOTICE ON 83(B)
ELECTIONS 
 IF YOU WISH TO MAKE A SECTION 83(B) ELECTION, THE FILING OF SUCH ELECTION IS YOUR RESPONSIBILITY. 

THE FORM FOR MAKING THIS SECTION 83(B) ELECTION IS ATTACHED TO THIS AGREEMENT. YOU MUST FILE THIS FORM WITHIN 30 DAYS OF THE GRANT DATE. 

YOU (AND NOT THE COMPANY, ANY OF ITS AGENTS OR ANY OTHER PERSON) SHALL BE SOLELY RESPONSIBLE FOR FILING SUCH FORM WITH THE IRS, EVEN IF YOU REQUEST THE
COMPANY, ITS AGENTS OR ANY OTHER PERSON TO MAKE THIS FILING ON YOUR BEHALF AND EVEN IF THE COMPANY, ANY OF ITS AGENTS OR ANY OTHER PERSON HAS PREVIOUSLY MADE THIS FILING ON YOUR BEHALF. 

The 83(b) election should be filed by mailing a signed election form by certified mail, return receipt requested to the IRS Service Center where you file your
tax returns. See www.irs.gov. 

 SECTION 83(B) ELECTION 

The undersigned hereby makes an election pursuant to Section 83(b) of the Internal Revenue Code of 1986, as amended, with respect to the property
described below and supplies the following information in accordance with Treas. Reg. § 1.83-2: 
  

	 	1.	 The name, address, and taxpayer identification number of the undersigned are: 

[Name] 
 [Address] 

[City, State Zip] 
 Taxpayer
Identification Number:
                                        

  

	 	2.	 The property with respect to which this election is being made is [______] shares of common stock, $0.001 par
value per share, of Decibel Therapeutics, Inc., a Delaware corporation (the “Company”). 

  

	 	3.	 The date on which the property was transferred or the date on which the restrictions on such property were
imposed, whichever is later, is _________________, 20[__] and the taxable year for which this election is being made is the calendar year 20[__]. 

  

	 	4.	 The property is subject to vesting provisions and may be forfeited under the terms of a stock restriction
agreement executed between the undersigned and the Company. 

  

	 	5.	 The fair market value of the property at the time of the transfer or the date on which the restrictions on such
property were imposed, whichever is later, (determined without regard to any lapse restriction, as defined in Treas. Reg. § 1.83-3(i)) is $[__________], equal to a fair market value of
$[__________] per share. 

  

	 	6.	 The amount paid for the property by the undersigned is $[__________]12, equal to a purchase price of $[__________] per share. 

 

	 	7.	 This statement is executed on _________________, 20[__]. 

In accordance with Treas. Reg. § 1.83-2(d) & (e)(7), a copy of this statement has been furnished to the
Company. 
  

	1 	 If restrictions are being added to previously unrestricted stock, the following language is to be used:
“[_____________] shares of the Company, having a fair market value of $[______________],” 

	2 	 If the shares were issued in exchange for an assignment of intellectual property rights, the following language
is to be used: “Intellectual property having a fair market value of $[______________],” 

					
	   
	 		 	   

	Signature of Taxpayer	 		 	Signature of Spouse (if any)

 SECTION 83(B) ELECTION 

BACKGROUND INFORMATION 

Section 83(b) of the Internal Revenue Code permits persons who receive restricted property, such as restricted stock, in connection with
the performance of services to include the value of such property in their gross income for the year the property is received. Such persons who purchase stock of the company subject to a stock restriction agreement providing for the vesting of such
stock over a period of time are entitled to make this election. Any person who makes a timely Section 83(b) election will recognize compensation income on the date of grant (the date listed in item 3 of the election form) equal to the
difference, if any, between the fair market value of the stock and the amount paid for the stock. A person who pays taxes in connection with an election and subsequently forfeits the stock, however, will not receive a refund or other tax benefit for
the taxes previously paid. 
 Any person who does not make the election will be required to include the value of the stock in gross income
in the year in which the stock vests. In particular, when the stock vests, the person will recognize compensation income in an amount equal to the difference between the fair market value of the stock on the vesting date and the amount paid for the
stock. As a result, if the value of the stock increases, a person who does not make a timely Section 83(b) election will have compensation income at the time each installment of stock vests. 

Each person should consult with his or her tax or legal advisor regarding the advisability and timing of filing the election. The original,
signed and dated Section 83(b) election must be filed within 30 days of the grant date but may be filed prior to the grant date. The election should be filed by certified mail, return receipt requested, with the Internal
Revenue Service at the service center where the electing person ordinarily files his or her annual tax return. A copy of the Section 83(b) election, as filed, must be returned to the company. A copy of the Section 83(b) election must also
be included with the person’s federal income tax return for the year of grant (each person should check with his or her tax preparer regarding this and any state, local, foreign or other filing requirements). 

Please also note that the certified mailing receipt for the Section 83(b) election should be retained. This receipt is essential if
the Internal Revenue Service does not receive the Section 83(b) election and challenges the election.

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