Audio test tones are a special class of artificially-created sounds. An example is the sine-wave tone you sometimes hear at the end of a video, or when a television station goes off the air.  Here are a couple of Apps for iPhone/iPad & Android that you can use to test or troubleshoot your AV system.
 
Audio Test Tones - Professional  (iPad / iPhone)

Test Tone Generator

https://itunes.apple.com/ca/app/audio-test-tones-professional/id356381704
 
Professional Audio Test Tones for testing your Audio Systems Equipment. Test speaker frequency ranges to specifications.
 
All Tones are Lossless WAV Format, 1 semitone files.
Tones include:
Sine Waves: 50Hz, 100Hz, 200Hz, 440Hz, 800Hz, 1kHz, 2kHz, 4kHz, 8kHz, 10kHz, 15kHz, 20kHz.
Square Waves: 50Hz, 100Hz, 200Hz, 440Hz, 800Hz, 1kHz, 2kHz, 4kHz, 8kHz, 10kHz, 15kHz, 20kHz.
 
Sweeps: (Loopable)
20Hz-10kHz, 20Hz-20kHz
50Hz-10kHz, 50Hz-20kHz
80Hz-10kHz, 80Hz-20kHz
 
Noise Generators:
White Noise
Pink Noise
Brown Noise
 
These are Professional Audio Test Tones to be used with a connected Audio System. These test tones are NOT intended to be used through the device's internal speakers nor through headphones. Use only with your iPhone or iTouch when connected via the speaker connection jack or an authorized dock. Some of these tones may not be audible to each individuals hearing range."

 

Pro Audio Tone Generator (Android)

https://play.google.com/store/apps/details?id=com.dutchmatic.patone&feature=search_result
 
A simple audio tool that provides live reference tones for a sound frequency response test.
- 1Hz to 20kHz bandwidth
- CD quality sampling at 16bits 44.1KHz
- digital frequency input (tap to set)
- 5 programmable frequency presets (long press)
- ultra low latency control slider
- built in oscillators for Sine, Square and Bopper waveforms
- stereo sound output switches for Left/Right ON/OFF
- high precision frequency control dial
- plays in background (home)

 

Disclaimer: we advise you to take care and caution in using these Apps. These independently produced Apps have only been reviewed by Advance System Design for inclusion in this article, quality assurance or application testing has not been done by advance System Design or affiliated parties. The following apps should be evaluated by your designated expert before use.