He clonado un repositorio existente y ahora estoy ejecutandobundle install - Por alguna razón falla en la gema de Ruby-Audio.

Installing ruby-audio (1.6.1) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

/Users/thisuser/.rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb 
checking for sndfile.h in /opt/local/include,/usr/local/include,C:/Program Files (x86)/Mega-Nerd/libsndfile/include,C:/Program Files/Mega-Nerd/libsndfile/include... no
checking for sf_open() in -lsndfile-1... no
checking for sf_open() in -lsndfile... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
--with-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/Users/thisuser/.rvm/rubies/ruby-1.9.3-p194/bin/ruby
--with-sndfile-dir
--without-sndfile-dir
--with-sndfile-include
--without-sndfile-include=${sndfile-dir}/include
--with-sndfile-lib
--without-sndfile-lib=${sndfile-dir}/lib
--with-sndfile-1lib
--without-sndfile-1lib
--with-sndfilelib
--without-sndfilelib
extconf.rb:26:in `<main>':   Can't find libsndfile (http://www.mega-nerd.com/libsndfile/) (RuntimeError)

  Try passing --with-sndfile-dir or --with-sndfile-lib and --with-sndfile-include
  options to extconf. If there are spaces in the path on windows, it may not work.

Gem files will remain installed in /Users/thisuser/.bundler/tmp/5253/gems/ruby-audio-1.6.1 for inspection.
Results logged to /Users/thisuser/.bundler/tmp/5253/gems/ruby-audio-1.6.1/ext/rubyaudio_ext/gem_make.out
An error occured while installing ruby-audio (1.6.1), and Bundler cannot continue.
Make sure that `gem install ruby-audio -v '1.6.1'` succeeds before bundling.

Honestamente, no tengo idea de qué hacer con esto. Googlear mostró el mismo error con la gema mysql, y las soluciones fueron específicas de mysql.

¿Alguien se ha topado alguna vez con esto? Si no es así, ¿hay alguna manera de decirle a los rieles que ignoren esa gema explícitamente? Eliminándolo del archivo gem y ejecutandobundle install De nuevo no hice el truco.

¡Gracias por cualquier ayuda!

Editar

despues de correrbrew install libsndfile Tengo la siguiente salida:

Warning: Your Xcode (4.5.2) is outdated
Please install Xcode 4.6.
==> Downloading http://www.mega-nerd.com/libsndfile/files/libsndfile-1.0.25.tar.gz
Already downloaded: /Library/Caches/Homebrew/libsndfile-1.0.25.tar.gz
==> Patching
patching file programs/sndfile-play.c
==> ./configure --prefix=/usr/local/Cellar/libsndfile/1.0.25
==> make install
make[1]: *** [sndfile-play.o] Error 1
make[1]: *** Waiting for unfinished jobs....
brew: superenv removed: -g -O2 -Wall -Wextra -Wdeclaration-after-statement -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes -Wcast-align -Wcast-qual -Wnested-externs -Wbad-function-cast -Wwrite-strings -Wundef
brew: superenv removed: -g -O2 -Wall -Wextra -Wdeclaration-after-statement -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes -Wcast-align -Wcast-qual -Wnested-externs -Wbad-function-cast -Wwrite-strings -Wundef
make: *** [install-recursive] Error 1
Your Xcode and or CLT are mis-configured. Try some or all of the following:
    xcrun --kill-cache
    xcodebuild -license
    sudo xcode-select -switch /path/to/Xcode.app

Intenté todos los comandos sugeridos, sin éxito. ¿Qué más puedo hacer para resolver esto?