On Hold Music & Cell Phones

Have you ever called a company on your cellphone, got put on hold and had to listen to staticky music? It’s happened to all of us. Dawn Hartford, Neltech Labs, explains why cell phones and music on hold don’t always sound crystal clear.

Cell phone callers typically experience a type of “active noise cancellation” or over-compression of the data stream from the cell phone to tower. This is happening in one of two places:

1. The cell phone itself is making the determination of what it thinks is an audio conversation – if a human is not talking then the phone may determine that the leftover background music track could be noise and they will hear periods of silence or a “shhhh” sound in the audio.

2. The other way is that the cell phone company is compressing the data as it travels from point-to-point. It is only compressing the data that the algorithm they are using determines is relevant – so, if it’s a phone conversation and not a data transfer, it is looking for a voice conversation. If the audio is not loud enough or the background music does not fit within the algorithms calculations then it removes that data during the compression process – almost like how an MP3 is compressed when using a low bit rate.

What are some solutions? 
1. Make the background music track a bit louder when the voice over track is not active.

2. Use a background music track that does not have a lot of periods with very low or very high frequency audio.

3. Have the end-user increase the volume of the audio player.

4. Make sure the customer does not have any type of AGC (Automatic Gain Control) set on the phone system.

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