<PAGE>
 
                                                                 Exhibit 10.15

                                 BUSINESS NOTE
                     (Use only for business purpose loans)

SONIC FOUNDRY, INC.               MARCH 3, 1999            $632,000.00
-----------------------------     ---------------    -----------------
         (MAKER)                       (DATE)

1. Promise to Pay and Payment Schedule. The undersigned ("Maker" whether one or
more) promises to pay to the order of Associated Bank South Central ("Lender")
at 1720 Monroe St., Madison 53711, Wisconsin, the sum of $632,000.00.

[Check (a), (b), (c) or (d); only one shall apply]

(a) [ ] Single Payment, In one payment on  N/A, plus interest payable as set
        forth below unless Interest is shown on line 4 below.

(b) [X] Installments of Principal and Interest in 35 equal payments of $5,050.00
        due on APRIL 3, 1999, and on
        [X] the same day of each succeeding month thereafter [ ] every 7th day
            thereafter [ ] every 14th day thereafter, PLUS a final payment of
            the unpaid balance and accrued interest due on MARCH 3, 2002, all
            subject to modification as set forth in 2(b) below, if applicable.
            All payments include principal and interest.

(c) [ ] Installments of Principal in  N/A  equal payments of principal of $  N/A
        due on  N/A  , and on
        [ ] the same day of each  N/A  month thereafter [ ] every 7th day
            thereafter [ ] every 14th day thereafter, PLUS a final payment of
            the unpaid principal due on  N/A  , PLUS interest payable as set
            forth below.

(d) [ ] Other  N/A

2. Interest Calculation. If the amount of interest is not shown on line 4 below,
   this Notes bears interest on the unpaid principal balance before maturity.
[Check (a), (b), or complete line 4 below; only one shall apply.]
(a) [X] Fixed Rate. At the rate of 7.375% per year.
(b) [ ] Variable Rate. At the annual rate which is equal to the following Index
        Rate, [ ] plus [ ] minus  N/A  percentage points ("Note Rate"), and the
        Note Rate shall be adjusted as provided below. The Index Rate is:
        [ ] The prime rate [ ] The reference rate [ ] The base rate adopted by
        [ ] Lender [ ]  N/A   N/A  from time to time as its base or reference
        rate for interest rate determinations. The Index Rate may or may not be
        the lowest rate charged by Lender.
        [ ]  N/A

        The Initial Note Rate is  N/A  %, An adjustment in the Note Rate will
        result in an increase or decrease in (1) [ ] the amount of each payment
        of interest, (2) [ ] the amount of the final payment, (3) [ ] the number
        of scheduled periodic payments sufficient to repay this Note in
        substantially equal payments, (4) [ ] the amount of each remaining
        payment of principal and interest so that those remaining payments will
        be substantially equal and sufficient to repay this Note by its
        scheduled maturity date, (5) [ ] the amount of each remaining payment of
        principal and interest (other than the final payment) so that those
        remaining payments will be substantially equal and sufficient to repay
        this Note by its scheduled maturity date based on the original
        amortization schedule used by Lender, plus the final payment of
        principal and interest, or (6) [ ]  N/A

        In addition, Lender is authorized to change the amount of periodic
        payments if and to the extent necessary to pay in full all accrued
        interest owing on this Note. The Maker agrees to pay any resulting
        payments or amounts. The Note Rate shall be adjusted only on the
        following change dates: [ ] the first day of each month [ ] each
        scheduled payment date [ ] as and when the Index Rate changes [ ]  N/A

Interest is computed for the actual number of days principal is unpaid on the
basis of [X] 360 day year [ ] 365 day year.
3. Interest Payment. Interest is payable on  N/A  , and on [ ] the same day of
each  N/A  month thereafter, [ ] every 7th day thereafter, [ ] every 14th day
thereafter and at maturity, or if box 1(b) is checked, at the times so
indicated.
4. Other Charges. If any payment (other than the final payment) is not made on
or before the 10th day after its due date. Lender may collect a delinquency
charge of 5.00% of the unpaid amount. Unpaid principal and interest bear
interest after maturity until paid (whether by acceleration or lapse of time)
all the rate [ ] rate otherwise be applicable plus  N/A  percentage points [X]
of 12.35% per year, computed on the basis of [X] a 360 day year [ ] a 365 year.
Maker agrees to pay a charge of 15.00 for each check presented for payment under
this Note which is returned unsatisfied.
5. Prepayment. Full or partial prepayment of this Note [X] is permitted at any
time without penalty [ ]  N/A .

            THIS NOTE INCLUDE ADDITIONAL PROVISIONS ON REVERSE SIDE.



                                        SONIC FOUNDRY
                                        --------------------------------(SEAL)

                                        BY /s/ KENNETH A. MINOR
                                        --------------------------------(SEAL)
                                        KENNETH A. MINOR    CFO

                                        BY /s/ RIMAS P. BUINEVICIUS
                                        --------------------------------(SEAL)
                                        RIMAS P. BUINEVICIUS CEO AND
                                                             CHAIRMAN

Inapplicable unless filled in           --------------------------------(SEAL)
(use for add on loans only).
1. Loan Proceeds         $ N/A          --------------------------------(SEAL)
2. Cr. Life Ins Charge     N/A          754 WILLIAMSON ST.
3. Cr A & B Ins. Charge    N/A          --------------------------------
4. Interest (Add-on)       N/A          MADISON, WI 53703
5.                         N/A          --------------------------------
6. Face Amount of Note     N/A                (ADDRESS)          (PHONE)
                         =======
------------------------------------------------------------------------------
                          FOR LENDER CLERICAL USE ONLY

If checked insert applicable prepayment restrictions and ??????
If credit life or accident and ?????? insurance is requested a ?????? may be
required.

L150
1st REN. & RENT ASSIGNMENTS                     6006 DENNIS SAMPSON
                                                --------------------------
                                                LOAN OFFICER
<PAGE>
 
                             ADDITIONAL PROVISIONS

     6. Default and Enforcement. If any installment is not paid when due under
this Note, If a default occurs under any other obligation of any Maker to Lender
or if Lender deems itself insecure, the unpaid balance shall, at the option of
Lender, without notice, mature and become immediately payable. The unpaid
balance shall automatically mature and become immediately payable in the event
any Maker, ?????, endorser or guarantor becomes the subject of bankruptcy or
other insolvency proceedings. Lender's rights and remedies upon such default. To
the extent not prohibited by law, Maker consents that ????? for any legal
proceeding relating to collection of this Note shall be, at Lenders option, the
country in which Lender has its principal office in this state, the county in
which any Maker resides or the county in which this Note was executed.

     7. Security. This Note is secured by all existing and future security
agreements and mortgages between Lender and Maker, between Lender and any
Indorser or guarantor of this Note, and between Lender and any other person
providing collateral security for Maker's obligations, and payment may be
accelerated according to any any of them. Unless a lien would be prohibited by
law or would render a nontaxable account taxable, Maker grants to Lender a
security interest and lien in any deposit account Maker may at any time have
with Lender. Lender may, at any time after an occurrence of an event of default,
without notice or demand, set-off against any deposit balances or other money
now or hereafter owed any Maker by Lender any amount unpaid under this Note.

     8. Rights and Lender. Without affecting the liability of any Maker,
indorser, surety, or guarantor, Lender may, without notice, accept partial
payments, release or impair any collateral security for the payment of this Note
or agree not to sue any party liable on its. Lender may apply prepayments, if
permitted, to such future installments as it elects. Lender may without notice
to Maker apply payments made by or for Maker to any obligations of Maker to
Lender, Without affecting the liability of any indorser, surety or guarantor,
Lender may from time to time, without notice, renew or excite the time for
prepayment.

     9. Obligations and Agreements of Maker. The obligations under this Note of
all Makers are joint and several. All Makers, Indorsers, ?????, and guarantors
agree to pay all costs of collection before and after judgement, including
reasonable attorney's fees (including those incurred in successful defense or
settlement of any counterclaim brought by Maker or incident to any action or
proceeding involving Maker brought pursuant to the United States Bankruptcy
Code) and waive presentment, protest, demand and notice of dishonor. Maker
agrees to indemnify and hold harmless Lender, its directors, officers, employees
and agents, from and against any and all claims, damages, judgements, penalties,
and expenses, including reasonable attorney's fees, arising directly or
indirectly from credit extended under this Note or the activities of Maker. This
Indemnity shall survive payment payment of this Note. Each Maker acknowledges
that Lender has not made any representations or warranties with respect to, and
that Lender does not assume any responsibility to Maker for, the collectability
of this Note or the financial condition of any Maker. Each Maker has
independently determined the collectability and enforceability of this Note.
Maker authorizes Lender to disclose financial and other information about Maker
to others.

     10. Interpretations. This note is intended by Maker and Lender as a final
expression of this Note and as a complete and exclusive statement of its terms,
there being no conditions to the enforceability of this Note. This Note may not
be supplemented or modified except in writing.