This is a frustrating fact for an audio engineer. You put time and energy into editing a voice over file so that it is clean and loud with no pops, clicks or breaths. You hand it over to your client and the next time you hear it over the telephone it sounds like a tinny fizzy mess. Okay, I am exaggerating, it does not always sound that bad, and the truth is, people generally do not notice as they are used to things sounding a certain way on the telephone.
However, when you compare it to the original pristine file, you will really notice the difference.
This is due to the fact that the telephone compresses the sound leaving out many of the frequencies. While this is usually acceptable for a voice, music does not always react well to having most of its frequencies stripped out.
Some music fares better than others, but some music does not translate well over the phone due it relying on the frequencies that have been taken out. Luckily, we have many tried and tested tracks that we use and can always swap them if the telephone system compresses it too much.
Why do telephones compress sound?
This was historically done to increase the number of conversations that could be had over a copper telephone line.
When things went digital computers started to compress the audio further and even more sound quality was lost. The video below explains it really well and in an entertaining way, but essentially the reason is down to compression and often several layers of it.
In the video, Tom talks about the sound quality getting worse. However, hopefully, things will improve as good quality VoIP becomes more widely used.
What are your thoughts? Feel free to comment and share