The Sound interface is suitable for playing back short audio files. New sound instances can be requested from LibGDX's Gdx.audio module using the newSound() method as follows:

Sound sound = Gdx.audio.newSound(Gdx.files.internal("sound.wav"));

This line of code will allocate new memory for the decoded audio data of the sound.wav file. The Sound interface also makes use of the Disposable interface, which implicates that the allocated resources need to be disposed manually using the respective dispose() method when a sound instance is no longer needed, as shown in the following code snippet:

sound.dispose(); // free allocated memory

Calling the play() method of a sound instance will start the playback of its audio data and will return an ID that is associated with the sound that is being played. A sound ID can be used to refer to a specific playing sound. This allows you to control sounds at a later time, such as stopping the playback and changing the volume, pitch, and pan.

There are several overloaded methods to start playing a sound for a single time or in an endless loop. Optionally, values for the sound's volume, pitch, and pan can also be passed as shown here:

long play();
long play(float volume);
long play(float volume, float pitch, float pan);
long loop();
long loop(float volume);
long loop(float volume, float pitch, float pan);

The value for volume ranges between 0.0 and 1.0, where higher values result in louder audio signals. Sounds can be pitched up and down resulting in lower or higher frequency audio signals, respectively. A pitch value of 1.0 will play the sound at its normal speed. Pitch values above 1.0 will let the sound play faster, while values below 1.0 will result in slower playback. A pan value of 0.0 will play the sound equally loud on the left and right audio channels, which is also referred to as the center. Negative pan values will play the sound only on the left audio channel whereas positive pan values will achieve the opposite.

Consider a scenario where we have two sounds, one for a cat and the other for a dog. Both sounds will be loaded in LibGDX as separate sound instances that can be used to play back several copies of them in parallel. To stop all playing copies of a (cat or dog) sound instance, the stop() method can be called. Alternatively, a sound ID can be passed to the stop() method to stop a specific copy of the (cat or dog) sound instance only, as shown here:

void stop();
void stop(long soundId);

Sounds that are currently playing can be modified using their sound ID and one of the following methods:

void setVolume(long soundId, float volume);
void setPan(long soundId, float pan, float volume);
void setPitch(long soundId, float pitch);
void setLooping(long soundId, boolean looping);

The Music interface is suitable for playing back long audio files and is designed in a very similar way when compared with the Sound interface. Therefore, new music instances can also be requested from LibGDX's Gdx.audio module; however, the method is called newMusic(), as shown here:

Music music = Gdx.audio.newMusic(Gdx.files.internal("music.mp3"));

The Music interface also makes use of the Disposable interface. The music instances that are no longer needed should always be disposed to free the allocated memory as follows:

music.dispose(); // free allocated memory

Apart from this, the interface provides the expected method to control music playback as follows:

void play();
void pause();
void stop();

Additionally, there are some methods to modify the music being played, as shown in the following listing:

void setPan(float pan, float volume);
void setVolume(float volume);
void setLooping(boolean isLooping);

At times, it might be useful to query the music for its state, such as its current position (in milliseconds) and whether it is still playing or not, as follows:

boolean isPlaying();
float getPosition();