Document:

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                                                                   EXHIBIT 4.7.6

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                   CHANCELLOR MEDIA CORPORATION OF LOS ANGELES

                                   as Obligor

                                       AND

                           the Guarantors named herein

                                       AND

                       U.S. TRUST COMPANY OF TEXAS, N.A.,

                                   as Trustee

                            -------------------------

                          FIFTH SUPPLEMENTAL INDENTURE

                           Dated as of August 23, 1999

                                       to

                                    Indenture

                          Dated as of February 14, 1996

                           --------------------------

                                  $200,000,000

                        9-3/8% Senior Subordinated Notes

                                    due 2004

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<PAGE>   2

         FIFTH SUPPLEMENTAL INDENTURE dated as of August 23, 1999, among
CHANCELLOR MEDIA CORPORATION OF LOS ANGELES, a Delaware corporation (the
"Company"), the subsidiaries listed on Schedule I hereto (collectively, the "New
Subsidiary Guarantors") and U.S. TRUST COMPANY OF TEXAS, N.A., a national
banking association, as Trustee (the "Trustee").

         WHEREAS, Chancellor Radio Broadcasting Company ("CRBC") (which, prior
to February 14, 1996, was known as Chancellor Broadcasting Company) and
Chancellor Broadcasting Licensee Company have heretofore executed and delivered
to the Trustee an Indenture dated as of February 14, 1996, as amended by that
certain First Supplemental Indenture, dated as of February 14, 1996, by and
among CRBC, the guarantors named therein and the Trustee, by that certain Second
Supplemental Indenture, dated as of April 15, 1997, by and among CRBC, the
guarantors named therein and the Trustee, by that certain Third Supplemental
Indenture, dated as of September 5, 1997, by and among the Company, the
guarantors named therein and the Trustee and by that certain Fourth Supplemental
Indenture, dated as of October 28, 1997 by and among the Company, the guarantors
named therein and the Trustee (as so amended, the "Indenture"), providing for
the issuance of $200,000,000 aggregate principal amount of 9-3/8% Senior
Subordinated Notes due 2004 (the "Notes"); and

         WHEREAS, pursuant to that certain Amended and Restated Agreement and
Plan of Merger by and among Chancellor Broadcasting Company, CRBC, Evergreen
Media Corporation, Evergreen Mezzanine Holdings Corporation and Evergreen Media
Corporation of Los Angeles, dated as of February 19, 1997 and amended and
restated as of July 31, 1997 (the "Merger Agreement"), among other things, (i)
Chancellor Broadcasting Company merged with and into Evergreen Mezzanine
Holdings Corporation (the "Parent Merger") and (ii) CRBC merged with and into
Evergreen Media Corporation of Los Angeles (the "Subsidiary Merger"). Upon
completion of the Parent Merger, Evergreen Media Corporation changed its name to
Chancellor Media Corporation and Evergreen Mezzanine Holdings Corporation
changed its name to Chancellor Mezzanine Holdings Corporation. Upon completion
of the Subsidiary Merger, Evergreen Media Corporation of Los Angeles changed its
name to Chancellor Media Corporation of Los Angeles; and

         WHEREAS, pursuant to that Third Supplemental Indenture dated as of
September 5, 1997, the Company assumed the obligations under the Notes and the
Indenture and the Company and the Trustee amended certain other terms of the
Indenture; and

         WHEREAS, the Company, the New Subsidiary Guarantors and the Trustee
desire by this Fifth Supplemental Indenture pursuant to and as contemplated by
the provisions of the Indenture relating to the addition of guarantors,
including Sections 4.19, 9.01 and 10A.03, to add the New Subsidiary Guarantors
as guarantors pursuant to the terms of the Indenture; and

         WHEREAS, the execution and delivery of this Fifth Supplemental
Indenture has been authorized by resolutions of the Boards of Directors of the
Company, and each of the New Subsidiary Guarantors; and

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         WHEREAS, all conditions and requirements necessary to make this Fifth
Supplemental Indenture a valid, binding legal instrument in accordance with its
terms have been performed and fulfilled by the parties hereto and the execution
and delivery thereof have been in all respects duly authorized by the parties
hereto.

         NOW, THEREFORE, in consideration of the above premises, each party
agrees, for the benefit of the others and for the equal and ratable benefit of
the holders of the Notes, as follows:

                                   ARTICLE I.

                     ASSUMPTION OF OBLIGATIONS AS GUARANTOR

Section 1.01. Assumption. Each of the New Subsidiary Guarantors hereby expressly
and unconditionally assumes each and every covenant, agreement and undertaking
of a Guarantor in the Indenture as of the date of this Fifth Supplemental
Indenture, and also hereby expressly and unconditionally assumes each and every
covenant, agreement and undertaking of a Guarantor in each Note outstanding on
the date of this Fifth Supplemental Indenture.

                                   ARTICLE II.

                            MISCELLANEOUS PROVISIONS

Section 2.01. Terms Defined. For all purposes of this Fifth Supplemental
Indenture, except as otherwise defined or unless the context otherwise requires,
terms used in capitalized form in this Fifth Supplemental Indenture and defined
in the Indenture have the meanings specified in the Indenture.

Section 2.02. Indenture. Except as amended hereby, the Indenture and the Notes
are in all respects ratified and confirmed and all the terms shall remain in
full force and effect.

Section 2.03. Governing Law. This FIFth Supplemental Indenture shall be governed
by and construed in accordance with the laws of the State of New York, as
applied to contracts made and performed within the State of New York, without
regard to principles of conflict of laws.

Section 2.04. Successors. All agreements of the Company and the New Subsidiary
Guarantors in this Fifth Supplemental Indenture and the Notes shall bind their
successors. All agreements of the Trustee in this Fifth Supplemental Indenture
shall bind its successors.

Section 2.05. Duplicate Originals. All parties may sign any number of copies of
this Fifth Supplemental Indenture. Each signed copy shall be an original, but
all of them together shall represent the same agreement.

Section 2.06. Severability. In case any one or more of the provisions in this
Fifth Supplemental Indenture or in the Notes shall be held invalid, illegal or
unenforceable, in any respect for any

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reason, the validity, legality and enforceability of any such provision in every
other respect and of the remaining provisions shall not in any way be affected
or impaired thereby, it being intended that all of the provisions hereof shall
be enforceable to the full extent permitted by law.

Section 2.07. Trustee Disclaimer. The Trustee accepts the amendment of the
Indenture effected by this Fifth Supplemental Indenture and agrees to execute
the trust created by the Indenture as hereby amended, but on the terms and
conditions set forth in the Indenture, including the terms and provisions
defining and limiting the liabilities and responsibilities of the Trustee, which
terms and provisions shall in like manner define and limit its liabilities and
responsibilities in the performance of the trust created by the Indenture as
hereby amended, and without limiting the generality of the foregoing, the
Trustee shall not be responsible in any manner whatsoever for or with respect to
any of the recitals or statements contained herein, all of which recitals or
statements are made solely by the Company and the New Subsidiary Guarantors, or
for or with respect to (i) the validity or sufficiency of this Fifth
Supplemental Indenture or any of the terms or provisions hereof, (ii) the proper
authorization hereof by the Company and the New Subsidiary Guarantors by
corporate action or otherwise, (iii) the due execution hereof by the Company and
the New Subsidiary Guarantors or (iv) the consequences (direct or indirect and
whether deliberate or inadvertent) of any amendment herein provided for, and the
Trustee makes no representation with respect to any such matters.

Section 2.08. Effectiveness. This Fifth Supplemental Indenture shall become
effective, once executed, upon receipt by the Trustee of a certificate of an
appropriate officer of the Company; and an opinion of Weil, Gotshal & Manges
LLP, counsel to the Company, each of which shall be dated no earlier than the
date hereof.

            (THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK)

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         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed as of the day and year written above.

                                         CHANCELLOR MEDIA CORPORATION
                                         OF LOS ANGELES, as Obligor

                                         /s/ William S. Banowsky, Jr.
                                         ---------------------------------------
                                         By:    William S. Banowsky, Jr.
                                         Title: Executive Vice President

Attest: /s/ Susan McGiffert
       ----------------------------

                                         On Behalf of Each of the New Subsidiary
                                         Guarantors Listed on Schedule I hereto

                                         /s/ William S. Banowsky, Jr.
                                         ---------------------------------------
                                         By:    William S. Banowsky, Jr.
                                         Title: Executive Vice President

Attest: /s/ Susan McGiffert
       ----------------------------
                                         U.S. TRUST COMPANY OF TEXAS, N.A.
                                         as Trustee

                                         /s/ John C. Stohlmann
                                         ---------------------------------------
                                         By:    John C. Stohlmann
                                         Title: Vice President

Attest: /s/ Melissa Scott
       ----------------------------

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                                   SCHEDULE I

                            NEW SUBSIDIARY GUARANTORS
                   (ALL NEW SUBSIDIARY GUARANTORS ARE DELAWARE
                  CORPORATIONS EXCEPT AS EXPRESSLY INDICATED)

The AMFM Radio Networks, Inc.
Chancellor Media Air Services Corporation
Chancellor Media Corporation of Michigan
Chancellor Media Corporation of New York
Chancellor Media Corporation of Ohio
Chancellor Media Martin Corporation
Chancellor Media MW Sign Corporation
Chancellor Media Nevada Sign Corporation
Chancellor Media Outdoor Corporation
Chancellor Media Radio Licenses, LLC (a Delaware limited liability company)
Chancellor Media/Shamrock Radio Licenses, LLC (a Delaware limited liability
  company)
Chancellor Media Whiteco Outdoor Corporation
Cleveland Radio Licenses, LLC (a Delaware limited liability company)
Dowling Company Incorporated (a Virginia corporation)
Hardin Development Corporation (a Florida corporation)
Martin Media, L.P. (a California limited partnership)
Outdoor Promotions West, LLC (a Delaware limited liability company)
Parsons Development Company (a Florida corporation)
Revolution Outdoor Advertising, Inc. (a Florida corporation)
Transit America Las Vegas, LLC (a Delaware limited liability company)
Triumph Outdoor Holdings, LLC (a Delaware limited liability company)
Triumph Outdoor Louisiana, LLC (a Delaware limited liability company)
Triumph Outdoor Rhode Island, LLC (a Delaware limited liability company)
Western Poster Service, Inc. (a Texas corporation)
Zebra Broadcasting Corporation (an Ohio corporation)

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                                                                   EXHIBIT 4.7.7

================================================================================

                               AMFM OPERATING INC.

                                   AS OBLIGOR

                                       AND

                           THE GUARANTORS NAMED HEREIN

                                       AND

                       U.S. TRUST COMPANY OF TEXAS, N.A.,

                                   AS TRUSTEE

                  --------------------------------------------

                          SIXTH SUPPLEMENTAL INDENTURE

                          DATED AS OF NOVEMBER 19, 1999

                                       TO

                                    INDENTURE

                          DATED AS OF FEBRUARY 14, 1996

                  --------------------------------------------

                                  $200,000,000

                    9 3/8% SENIOR SUBORDINATED NOTES DUE 2004

================================================================================

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     SIXTH SUPPLEMENTAL INDENTURE dated as of November 19, among AMFM OPERATING,
INC. a Delaware corporation (formerly Capstar Communications, Inc., the
"Company"), the subsidiaries listed on Schedule I hereto (collectively, the "New
Subsidiary Guarantors") and U.S. TRUST COMPANY OF TEXAS, N.A., a national
banking association, as Trustee (the "Trustee").

     WHEREAS, Chancellor Radio Broadcasting Company ("CRBC") (which, prior to
February 14, 1996, was known as Chancellor Broadcasting Company) and Chancellor
Broadcasting Licensee Company have heretofore executed and delivered to the
Trustee an Indenture dated as of February 14, 1996, as amended by that certain
First Supplemental Indenture dated as of February 14, 1996 by and among CRBC,
the guarantors named therein and the Trustee, by that certain Second
Supplemental Indenture dated as of April 15, 1997 by and among CRBC, the
guarantors named therein and the Trustee, by that certain Third Supplemental
Indenture dated as of September 5, 1997 by and among Chancellor Media
Corporation of Los Angeles ("CMCLA"), the guarantors named therein and the
Trustee, by that certain Fourth Supplemental Indenture dated as of October 28,
1997 by and among CMCLA, the guarantors named therein and the Trustee, and by
that certain Fifth Supplemental Indenture dated as of August 23, 1999 by and
among CMCLA, the guarantors named therein and the Trustee (as so amended, the
"Indenture"), providing for the issuance of $200,000,000 aggregate principal
amount of 93/8% Senior Subordinated Notes due 2004 (the "Notes");

     WHEREAS, pursuant to that Third Supplemental Indenture, dated as of
September 5, 1997, CMCLA assumed the obligations under the Notes and the
Indenture, and CMCLA and the Trustee amended certain other terms of the
Indenture;

     WHEREAS, pursuant to that certain Agreement and Plan of Merger by and among
CMCLA, Capstar Radio Broadcasting Partners, Inc., a Delaware corporation
("Capstar Radio"), SBI Holding Corporation, a Delaware corporation ("SBI"), and
the Company, dated as of November 19, 1999 (the "Merger Agreement"), among other
things, CMCLA, Capstar Radio, and SBI merged with and into the Company (the
"Merger");

     WHEREAS, the Company, the New Subsidiary Guarantors and the Trustee desire
by this Sixth Supplemental Indenture (i) pursuant to and as contemplated by
Section 5.01(a)(1)(B) of the Indenture, that the Company expressly assume all of
the obligations under the Notes and the Indenture, and (ii) pursuant to and as
contemplated by the provisions of the Indenture relating to the addition of
guarantors, including Sections 4.19, 9.01 and 10A.03, to add the New Subsidiary
Guarantors as guarantors pursuant to the terms of the Indenture;

     WHEREAS, the execution and delivery of this Sixth Supplemental Indenture
has been authorized by resolutions of the Boards of Directors of the Company and
each of the New Subsidiary Guarantors; and

     WHEREAS, all conditions and requirements necessary to make this Sixth
Supplemental Indenture a valid, binding legal instrument in accordance with its
terms have been performed and fulfilled by the parties hereto and the execution
and delivery thereof have been in all respects duly authorized by the parties
hereto.

<PAGE>   3

     NOW, THEREFORE, in consideration of the above premises, each party agrees,
for the benefit of the others and for the equal and ratable benefit of the
holders of the Notes, as follows:

                                    ARTICLE I

                       ASSUMPTION OF OBLIGATIONS AS ISSUER

     Section 1.01 ASSUMPTION. The Company hereby expressly and unconditionally
assumes each and every covenant, agreement and undertaking of CMCLA under the
Indenture as of the date of this Sixth Supplemental Indenture, and also hereby
expressly and unconditionally assumes each and every covenant, agreement and
undertaking of CMCLA under each Note outstanding on the date of this Sixth
Supplemental Indenture.

                                   ARTICLE II

                     ASSUMPTION OF OBLIGATIONS AS GUARANTOR

     Section 2.01 ASSUMPTION. Each of the New Subsidiary Guarantors hereby
expressly and unconditionally assumes each and every covenant, agreement and
undertaking of a Guarantor in the Indenture as of the date of this Sixth
Supplemental Indenture, and also hereby expressly and unconditionally assumes
each and every covenant, agreement and undertaking of a Guarantor in each Note
outstanding on the date of this Sixth Supplemental Indenture.

                                   ARTICLE III

                            MISCELLANEOUS PROVISIONS

     Section 3.01 DEFINED TERMS. For all purposes of this Sixth Supplemental
Indenture, except as otherwise defined or unless the context otherwise requires,
terms used in capitalized form in this Sixth Supplemental Indenture and defined
in the Indenture have the meanings specified in the Indenture.

     Section 3.02 INDENTURE. Except as amended hereby, the Indenture and the
Notes are in all respects ratified and confirmed and all the terms shall remain
in full force and effect.

     Section 3.03 GOVERNING LAW. THIS SIXTH SUPPLEMENTAL INDENTURE SHALL BE
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK,
AS APPLIED TO CONTRACTS MADE AND PERFORMED WITHIN THE STATE OF NEW YORK, WITHOUT
REGARD TO PRINCIPLES OF CONFLICT OF LAWS.

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     Section 3.04 SUCCESSORS. All agreements of the Company and the New
Subsidiary Guarantors in this Sixth Supplemental Indenture and the Notes shall
bind their successors. All agreements of the Trustee in this Sixth Supplemental
Indenture shall bind its successors.

     Section 3.05 DUPLICATE ORIGINALS. All parties may sign any number of copies
of this Sixth Supplemental Indenture. Each signed copy shall be an original, but
all of them together shall represent the same agreement.

     Section 3.06 SEVERABILITY. In case any one or more of the provisions in
this Sixth Supplemental Indenture or in the Notes shall be held invalid, illegal
or unenforceable, in any respect for any reason, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions shall not in any way be affected or impaired thereby, it being
intended that all of the provisions hereof shall be enforceable to the full
extent permitted by law.

     Section 3.07 TRUSTEE DISCLAIMER. The Trustee accepts the amendment of the
Indenture effected by this Sixth Supplemental Indenture and agrees to execute
the trust created by the Indenture as hereby amended, but on the terms and
conditions set forth in the Indenture, including the terms and provisions
defining and limiting the liabilities and responsibilities of the Trustee, which
terms and provisions shall in like manner define and limit its liabilities and
responsibilities in the performance of the trust created by the Indenture as
hereby amended, and without limiting the generality of the foregoing, the
Trustee shall not be responsible in any manner whatsoever for or with respect to
any of the recitals or statements contained herein, all of which recitals or
statements are made solely by the Company and the New Subsidiary Guarantors, or
for or with respect to (i) the validity or sufficiency of this Sixth
Supplemental Indenture or any of the terms or provisions hereof, (ii) the proper
authorization hereof by the Company and the New Subsidiary Guarantors by
corporate action or otherwise, (iii) the due execution hereof by the Company and
the New Subsidiary Guarantors or (iv) the consequences (direct or indirect and
whether deliberate or inadvertent) of any amendment herein provided for, and the
Trustee makes no representation with respect to any such matters.

     Section 3.08 EFFECTIVENESS. This Sixth Supplemental Indenture shall become
effective, once executed, upon receipt by the Trustee of a certificate of the
appropriate officers of the Company; and an opinion of Vinson & Elkins L.L.P.,
counsel to the Company, each of which shall be dated no earlier than the date
hereof.

            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]

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     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed as of the day and year written above.

                                        AMFM OPERATING INC.,
                                        as Obligor

                                        By: /s/ W. Schuyler Hansen
                                           -------------------------------------
                                            W. Schuyler Hansen
                                            Senior Vice President and
                                            Chief Accounting Officer

Attest:  /s/ Jean Menke
       ------------------------------

                                        ON BEHALF OF EACH OF THE NEW SUBSIDIARY
                                        GUARANTORS LISTED ON SCHEDULE I HERETO*

                                        By: /s/ Kathy Archer
                                           -------------------------------------
                                            Kathy Archer
                                            Senior Vice President

Attest:  /s/ Jean Menke
       ------------------------------

                                        U.S. TRUST COMPANY OF TEXAS, N.A.,
                                        as Trustee

                                        /s/ Bill Barber
                                        ----------------------------------------
                                        By:  Bill Barber
                                             -----------------------------------
                                        Title:  Vice President
                                               ---------------------------------

Attest:  /s/ Peg Makowski
       ------------------------------

--------
*For Capstar TX Limited Partnership, by Capstar Radio Operating Company, its
general partner.

<PAGE>   6

                                         CAPSTAR ROYALTY I CORPORATION
                                         CAPSTAR ROYALTY II CORPORATION
                                         CAPSTAR COMMUNICATIONS OF
                                              CALIFORNIA, INC.,
                                         as New Subsidiary Guarantors

                                         By:  /s/ Kathy Archer
                                             -----------------------------------
                                              Kathy Archer
                                              President

Attest: /s/ Jean Menke
       ------------------------------

<PAGE>   7

                                   SCHEDULE I

                           NEW SUBSIDIARY GUARANTORS
            (ALL NEW SUBSIDIARY GUARANTORS ARE DELAWARE CORPORATIONS
                         EXCEPT AS EXPRESSLY INDICATED)

Chancellor Media Corporation of California
Chancellor Media Corporation of the Lone Star State
Chancellor Media Licensee Company
Chancellor Media Pennsylvania License Corp.
KZPS/KDGE License Corp.
Chancellor Marketing Group, Inc. (a Virginia corporation)
CBC Acquisition Company, Inc.
Capstar Acquisition Company, Inc.
Capstar Operating Corporation
Capstar Royalty II Corporation
Osborn Entertainment Enterprises Corporation
Music Hall Club, Inc. (a West Virginia corporation)
Jamboree in the Hills
Capstar Royalty I Corporation
Triathlon Broadcasting Company
Capstar Communications California, Inc.
Capstar Radio Operating Company
WPYX, Inc. (a New York corporation)
Capstar TX Limited Partnership (a Delaware limited partnership)

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