UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                 SCHEDULE 13D/A
                        Under the Securities Act of 1934
                                (Amendment No. 8)

                        Natus Medical Incorporated (BABY)
                                (Name of Issuer)

                                  Common Stock
                         (Title of Class of Securities)

                                    639050103
                                 (CUSIP Number)

                                David Nierenberg

                               The D3 Family Funds

                               19605 NE 8th Street

                                 Camas, WA 98607

                                  360-604-8600
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                October 18, 2005
             (Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D and is filing this
schedule because of ss.ss.240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box: |_|



--------------------------------------------------------------------------------
1    NAME OF REPORTING PERSON
     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

     The D3 Family Fund, L.P. (David Nierenberg is president of the General
     Partner, which is Nierenberg Investment Management Company.)
--------------------------------------------------------------------------------
2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                 (a)  |X|
                                                                 (b)  |_|
--------------------------------------------------------------------------------
3    SEC USE ONLY


--------------------------------------------------------------------------------
4    SOURCE OF FUNDS

     WC
--------------------------------------------------------------------------------
5    CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
     PURSUANT TO ITEMS 2(d) OR 2(e)                                   |_|


--------------------------------------------------------------------------------
6    CITIZENSHIP OR PLACE OF ORGANIZATION

     Washington
--------------------------------------------------------------------------------
               7    SOLE VOTING POWER

                    1,686,422 common shares (9.4%)
               -----------------------------------------------------------------
  NUMBER OF    8    SHARED VOTING POWER
   SHARES
BENEFICIALLY        0
  OWNED BY     -----------------------------------------------------------------
    EACH       9    SOLE DISPOSITIVE POWER
  REPORTING
   PERSON           1,686,422
    WITH       -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER

                    0
--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     3,508,914 shares (19.59%)
--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES   |_|


--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

     19.59%
--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON

     PN
--------------------------------------------------------------------------------


                                       2


--------------------------------------------------------------------------------
1    NAME OF REPORTING PERSON
     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

     The D3 Family Retirement Fund, L.P. (David Nierenberg is president of the
     General Partner, which is Nierenberg Investment Management Company.)
--------------------------------------------------------------------------------
2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                 (a)  |X|
                                                                 (b)  |_|
--------------------------------------------------------------------------------
3    SEC USE ONLY


--------------------------------------------------------------------------------
4    SOURCE OF FUNDS

     WC
--------------------------------------------------------------------------------
5    CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
     PURSUANT TO ITEMS 2(d) OR 2(e)                                   |_|


--------------------------------------------------------------------------------
6    CITIZENSHIP OR PLACE OF ORGANIZATION

     Washington
--------------------------------------------------------------------------------
               7    SOLE VOTING POWER

                    551,940 shares (3.0%)
               -----------------------------------------------------------------
  NUMBER OF    8    SHARED VOTING POWER
   SHARES
BENEFICIALLY        0
  OWNED BY     -----------------------------------------------------------------
    EACH       9    SOLE DISPOSITIVE POWER
  REPORTING
   PERSON           551,940
    WITH       -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER

                    0
--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     3,508,914 shares (19.59%)
--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES   |_|


--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

     19.59%
--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON

     PN
--------------------------------------------------------------------------------


                                       3


--------------------------------------------------------------------------------
1    NAME OF REPORTING PERSON
     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

     The D3 Children's Fund, L.P. (David Nierenberg is president of the General
     Partner, which is Nierenberg Investment Management Company.)
--------------------------------------------------------------------------------
2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                 (a)  |X|
                                                                 (b)  |_|
--------------------------------------------------------------------------------
3    SEC USE ONLY


--------------------------------------------------------------------------------
4    SOURCE OF FUNDS

     WC
--------------------------------------------------------------------------------
5    CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
     PURSUANT TO ITEMS 2(d) OR 2(e)                                   |_|


--------------------------------------------------------------------------------
6    CITIZENSHIP OR PLACE OF ORGANIZATION

     Washington
--------------------------------------------------------------------------------
               7    SOLE VOTING POWER

                    132,161 common shares (0.7%)
               -----------------------------------------------------------------
  NUMBER OF    8    SHARED VOTING POWER
   SHARES
BENEFICIALLY        0
  OWNED BY     -----------------------------------------------------------------
    EACH       9    SOLE DISPOSITIVE POWER
  REPORTING
   PERSON           132,161
    WITH       -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER

                    0
--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     3,508,914 shares (19.59%)
--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES   |_|


--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

     19.59%
--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON

     PN
--------------------------------------------------------------------------------


                                       4


--------------------------------------------------------------------------------
1    NAME OF REPORTING PERSON
     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

     The D3 Offshore Fund, L.P. (David Nierenberg is president of the General
     Partner, which is Nierenberg Investment Management Company.)
--------------------------------------------------------------------------------
2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                 (a)  |X|
                                                                 (b)  |_|
--------------------------------------------------------------------------------
3    SEC USE ONLY


--------------------------------------------------------------------------------
4    SOURCE OF FUNDS

     WC
--------------------------------------------------------------------------------
5    CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
     PURSUANT TO ITEMS 2(d) OR 2(e)                                   |_|


--------------------------------------------------------------------------------
6    CITIZENSHIP OR PLACE OF ORGANIZATION

     Bahamas
--------------------------------------------------------------------------------
               7    SOLE VOTING POWER

                    826,158 common shares (4.6%)
               -----------------------------------------------------------------
  NUMBER OF    8    SHARED VOTING POWER
   SHARES
BENEFICIALLY        0
  OWNED BY     -----------------------------------------------------------------
    EACH       9    SOLE DISPOSITIVE POWER
  REPORTING
   PERSON           826,158
    WITH       -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER

                    0
--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     3,508,914 shares (19.59%)
--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES   |_|


--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

     19.59%
--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON

     PN
--------------------------------------------------------------------------------


                                       5


--------------------------------------------------------------------------------
1    NAME OF REPORTING PERSON
     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

     The D3 Family Bulldog Fund, L.P. (David Nierenberg is president of the
     General Partner, which is Nierenberg Investment Management Company.)
--------------------------------------------------------------------------------
2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                 (a)  |X|
                                                                 (b)  |_|
--------------------------------------------------------------------------------
3    SEC USE ONLY


--------------------------------------------------------------------------------
4    SOURCE OF FUNDS

     WC
--------------------------------------------------------------------------------
5    CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
     PURSUANT TO ITEMS 2(d) OR 2(e)                                   |_|


--------------------------------------------------------------------------------
6    CITIZENSHIP OR PLACE OF ORGANIZATION

     Washington
--------------------------------------------------------------------------------
               7    SOLE VOTING POWER

                    312,233 common shares (1.7%)
               -----------------------------------------------------------------
  NUMBER OF    8    SHARED VOTING POWER
   SHARES
BENEFICIALLY        0
  OWNED BY     -----------------------------------------------------------------
    EACH       9    SOLE DISPOSITIVE POWER
  REPORTING
   PERSON           312,233
    WITH       -----------------------------------------------------------------
               10   SHARED DISPOSITIVE POWER

                    0
--------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     3,508,914 shares (19.59%)
--------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES   |_|


--------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

     19.59%
--------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON

     PN
--------------------------------------------------------------------------------


                                       6


Item 1. Security and Issuer.

            Common stock of Natus Medical  Incorporated,  1501 Industrial  Road,
            San Carlos, CA 94070

Item 2. Identity and Background.

            The D3 Family Funds are Washington State limited partnerships, whose
            principal  business is investing in the equities of public micro-cap
            issuers.  The D3 Family Funds  consist of: D3 Family  Fund,  L.P, D3
            Family  Retirement  Fund, L.P, D3 Children's  Fund, L.P, D3 Offshore
            Fund,  L.P., D3 Family Bulldog Fund, L.P.  Located at 19605 N.E. 8th
            St.,  Camas,  Washington  98607.  No convictions  or  administrative
            proceedings as described in 2 (d) and (e).

Item 3. Source and Amount of Funds or Other Consideration

            Source  of funds  is money  invested  in the  partnerships  by their
            partners.

Item 4. Purpose of Transaction

            We  acquired  an  additional  600,000  shares of BABY as a long term
            investment.

            Before  this  most  recent  investment,   we  already  had  built  a
            substantial  investment  in BABY  for  the  following  reasons:  the
            company's  strong  market  share  and  recurring  revenues  from the
            newborn hearing screening  business,  the company's excellent growth
            prospects as newborn  hearing  screening  becomes the  medical-legal
            standard of care in developed  foreign markets just as it has become
            the gold  standard  here in the United  States,  the  prospects  for
            additional  growth through  pediatric  hearing screening and newborn
            phototherapy, and the strong management of the company.

            BABY's  acquisition  of and merger  with BLSC is a company  building
            event,  one  which  increases  further  our  already  high  level of
            enthusiasm for the company.  It combines two of the leading  newborn
            hearing  screening  companies with multiple  modalities,  capable of
            addressing  customer  needs in the full  range of  applications  and
            environments.  It complements BABY's franchise among  neonatologists
            with  BLSC's  franchise  with  audiologists  and  neurologists.   It
            combines hearing screening and hearing diagnostic products under the
            same company and creates the potential for future products which may
            combine  both   screening   and  precise   diagnostics   capability,
            potentially  giving the combined company the opportunity to become a
            global leader in the overall hearing business. It complements BABY's
            historic  strengths  in sales and service  with BLSC's  strengths in
            technology and BLSC's  relationships  with leading  clinicians.  The
            acquisition  brings new products  which the combined sales force can
            sell  into  neonatal  and  pediatric   applications   in  sleep  and
            neurology. The acquisition should enhance BLSC's ability to sell its
            products abroad,  particularly  into those developed


                                       7


            country markets where BABY already has sufficient  scale to have its
            own direct distribution.

            The acquisition looks reasonably priced to us when one considers the
            amount  of cash on  BLSC's  balance  sheet and the value of its real
            estate.  Similarly, from a prospective earnings point of view, there
            will be an opportunity to eliminate  duplicated public company costs
            as well as numerous other savings opportunities  throughout the cost
            structures  of both  companies.  We would  not be  surprised  if the
            combined  company  were  capable of earning  65-70  cents per share,
            annualized,  in 2006, and considerably more in the future,  once new
            generations of products a are developed and marketed.

            We congratulate both companies on this shrewd move and are delighted
            to be the largest shareholder.

Item 5. Interest in Securities of the Issuer.

            (a,b) D3 Family Funds own and have sole voting and dispositive power
                  over 3,508,914, 19.59% common shares of BABY.



            (c)   Fund                                Date     Shares Bought  Price
                                                                     
                  D3 Family Fund, L.P.             10/18/2005     143,000     11.88
                  D3 Family Retirement Fund, L.P.  10/18/2005      58,000     11.88
                  D3 Children's Fund, L.P.         10/18/2005      30,000     11.88
                  D3 Offshore Fund, L.P.           10/18/2005     325,000     11.88
                  D3 Family Bulldog Fund, L.P.     10/18/2005      44,000     11.88


            (d)   N/A

            (e)   N/A

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to
        Securities of the Issuer.

            N/A

Item 7. Material to be Filed as Exhibits

            N/A


                                       8


                                    SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, each of the
undersigned  certifies that the  information set forth in the Statement is true,
complete and correct.


      October 18, 2005                  /s/ DAVID NIERENBERG
      ----------------                  -------------------------------------
                                        President
                                        Nierenberg Investment Management
                                        Company, Inc., the General Partner of
                                        The D3 Family Funds.


                                       9