<PAGE>   1
                                                                   EXHIBIT 10.31

                             STOCK OPTION AGREEMENT

                                                Dated as of: September 10, 1996

To:  [See List of Option Grants]

     Pursuant to resolutions of the Board of Directors of Somanetics
Corporation, a Michigan corporation (the "Company"), the Company hereby grants
to you an option (the "Option") to purchase up to ______________ (_____) Common
Shares, par value $.01 per share, of the Company (the "Shares") at $__.__ per
Share, upon the terms and conditions contained herein.

     1. The Option herein granted may not be transferred by you otherwise than
by will or by the laws of descent and distribution, and during your lifetime
the Option is exercisable only by you.

     2. (a) Subject to the other terms of this Option, you may exercise the
Option in accordance with the following schedule:

        (i) Between the date of this Option and September 10, 1997, none of the
     Shares may be purchased,

        (ii) Commencing September 10, 1997 one-fourth (1/4) of the Shares may
     be purchased.

        (iii) Commencing September 10, 1998, an additional one-fourth (1/4), of
     the Shares may be purchased.

        (iv) Commencing September 10, 1999, an additional one-fourth (1/4), of
     the Shares may be purchased.

        (v) Commencing September 10, 2000, the final one-fourth (1/4) of the
     Shares may be purchased.

Notwithstanding anything in this Option to the contrary, the Option shall be
exercisable to purchase all of the Shares immediately, to the extent not
already purchased, (i) ten (10) business days before the consummation of a
"Transaction" as defined in Paragraph 17 of the Somanetics Corporation 1991
Incentive Stock Option Plan (the "1991 Plan"), which definition is incorporated
into this Option by reference and shall bind you and the Company as if set
forth in full in this Option, and (ii) upon the acquisition by any person,
entity or group (as defined pursuant to Section 13(d) of the Securities
Exchange Act of 1934, as amended) of 51% or more of the Company's outstanding
voting securities.

<PAGE>   2



        (b) Subject to earlier termination in accordance with the provisions of
Paragraphs 11, 12 and 14 of the 1991 Plan (which provisions are incorporated
into this option by reference and shall bind you and the Company as if set
forth in full in this Option; references in such Paragraphs 11, 12 and 14 to
"Participant", "option", "Nonqualified Option" and "Plan" shall be deemed
references to you, this Option, this Option and this Option, respectively, for
all purposes under this Option), the Option shall expire (to the extent not
previously exercised) on September 10, 2006.

     3. The Option shall be exercised by giving a written notice of exercise to
the Treasurer of the Company.  Such notice shall specify the number of Shares
to be purchased and shall be accompanied by payment in full (in the manner set
forth in Paragraph 9 of the 1991 Plan, which paragraph is incorporated into
this Option by reference and shall bind you and the Company as if set forth in
full in this Option) of the aggregate option price for the number of Shares
purchased.  The Company shall cause the Common Shares underlying the Option to
be registered with the Securities and Exchange Commission pursuant to the
Securities Act of 1933, as amended, on the appropriate form and as required
under any applicable state or foreign securities or Blue Sky laws.  Such
exercise shall be effective only upon the actual receipt of such written notice
and of the option price, and no rights or privileges of a shareholder of the
Company in respect of any of the Shares issuable upon the exercise of any part
of the Option shall inure to you, or any other person entitled to exercise the
Option, unless and until certificates representing such Shares shall have been
issued, and prior to such issuance no adjustment shall be made for dividends,
distributions or other rights in respect of such Shares, except as provided in
paragraphs 6 and 7.

     4. If upon the exercise of the Option there shall be payable by the
Company or a subsidiary any amount for income tax withholding, in the Company's
Board of Directors' sole discretion, either you shall pay such amount to the
Company, or the number of Shares delivered by the Company to you shall be
appropriately reduced, to reimburse the Company for such payment.  The
Company's Board of Directors may, in its sole discretion, permit you to satisfy
such withholding obligations, in whole or in part, by electing to have the
number of Shares delivered or deliverable by the Company upon exercise of  this
Option appropriately reduced, or by electing to tender Common Shares back to
the Company subsequent to exercise of the Option, to reimburse the Company for
such income tax withholding.  The Company's Board of Directors may make such
other arrangements with respect to income tax withholding as it shall
determine.

     5. It is understood and agreed that nothing contained in this Agreement,
nor any action taken by the Board, shall confer upon you any right with respect
to the continuation of your employment by the Company or any subsidiary, nor
interfere in any way with the right of the Company or a subsidiary to terminate
your employment at any time.


                                     -2-

<PAGE>   3


     6. The provisions set forth in Paragraph 17 of the 1991 Plan are
incorporated into this Option by reference and shall bind you and the Company
as if set forth in full in this Option.  References in such Paragraph 17 to
"Participant", "stock option" and "Plan" shall be deemed references to you,
this Option and this Option, respectively, for all purposes under this Option.

     7. Subject to Paragraph 17 of the 1991 Plan, the number and type of shares
subject to the Option and the option price with respect to the Option shall be
subject to such adjustment as the Committee (as defined in Paragraph 1(b) of
the 1991 Plan, which definition is incorporated into this Option by reference
and shall bind you and the Company as if set forth in full in this Option), in
its discretion, deems appropriate to reflect such events as stock dividends,
stock splits, recapitalizations, mergers, statutory share exchanges or
reorganizations of or by the Company, such adjustments to be the same as the
adjustments such Committee deems appropriate for options outstanding under the
1991 Plan; provided that no adjustment shall be made in connection with any
conversion of the Company's outstanding Convertible Preferred Shares.  However,
no fractional shares shall be issued pursuant to the Option, and any fractional
shares resulting from such adjustments shall be eliminated from this Option.


                                        Very truly yours,      
                                                               
                                        SOMANETICS CORPORATION,
                                        a Michigan corporation 
                                                               
                                                               
                                                               
                                        By______________________
                                                               
                                        Its_____________________


The above is agreed to and
accepted.




__________________________


Dated:____________________



                                     -3-