# How to make recorded audio sound like telephone audio? **URL:** \ **Category:** Factual Questions\ **Created:** [September 13, 2005, 10:57pm UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506 "2005-09-13T22:57:38Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Jayrot](https://avatars.discourse-cdn.com/v4/letter/j/3ec8ea/32.png) [@Jayrot](https://boards.straightdope.com/u/Jayrot)\ **Post date:** [September 13, 2005, 10:57pm UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/1 "2005-09-13T22:57:38Z")
For a project I’m working on, I’d like to make some of the voice audio I’ve recorded (.wav) to sound like it’s coming through a telelphone to simulate a radio call-in show. I know it has to do with some kind of filter and perhaps down sampling (8khz?) but can someone explain exactly how to do it spefically – which program, which functions? Thanks. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [September 13, 2005, 11:04pm UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/2 "2005-09-13T23:04:18Z")
Have you thought about just recording the telephone’s normal static and mixing it with your voice recording? ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [September 13, 2005, 11:14pm UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/3 "2005-09-13T23:14:03Z")
IANAn audio guy, but I took a spoken word wav file and subjected it to a high pass filter found in [Audacity](http://audacity.sourceforge.net/) and it kinda sounds a like it’s coming over the phone. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [September 13, 2005, 11:22pm UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/4 "2005-09-13T23:22:09Z")
Wash your sound through a low cut at 300 Hz and a high cut at 3400 KHz and you’re pretty much there. If you’ve got something to reduce the dynamic range, that’d also be worth playing with. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [September 13, 2005, 11:25pm UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/5 "2005-09-13T23:25:24Z")
Telephones have a very narrow bandwidth. Find some sort of graphic equalizer (Windows Media Player has one) and do your best to kill off everything below 300 Hz and above 4 KHz (4,000 Hz). This should give the voice that distinctive “tinny” telephone sound. ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [September 13, 2005, 11:35pm UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/6 "2005-09-13T23:35:39Z")
Using a very low sampling rate is probably the easiest (if not the best) way. You can do this with the tiny “Sound Recorder” program that comes with Windows. Just open the file, then Save As… and somewhere in there is a button/tab that says “quality” or “rate” or something. Bring it way down and see how it sounds. Be sure to keep the original saved so you can undo it. ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [September 14, 2005, 12:53am UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/7 "2005-09-14T00:53:54Z")
Silly idea, but why not reciord through a phone? You can get a device at radio shack that plugs into the handset jack of a standard phone that provides a microphone output. ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [September 14, 2005, 1:50am UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/8 "2005-09-14T01:50:32Z")
An important part of the “telephone sound” is the carbon microphone used in the handset. It introduces noticeable amounts of noise and distortion. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [September 14, 2005, 2:07am UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/9 "2005-09-14T02:07:10Z")
> [@mks57](#): > > An important part of the “telephone sound” is the carbon microphone used in the handset. It introduces noticeable amounts of noise and distortion. No phones use carbon microphones anymore. I haven’t even _seen_ one in well over 15 years. They almost all use either voice coil or piezoelectric mics these days. ---
**Author:** ![galt](https://avatars.discourse-cdn.com/v4/letter/g/35a633/32.png) [@galt](https://boards.straightdope.com/u/galt)\ **Post date:** [September 14, 2005, 2:31am UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/10 "2005-09-14T02:31:05Z")
If the Adobe Audition “Telephone handset” FFT preset is any indication, you want it to cut off everything below 300Hz, then exponentially ramp up so that at 1600Hz, it’s full strength until you get to 3300Hz, where it drops off linearly to 0% strength at 4000Hz. Here’s a kind of ugly ASCII art rendition of the filter: ```auto 100-| BxxxxxxxC | x x | x x | x x | x x | x x | xx x | xxx x 0---| xxxA Dxxxxxxx --------------------------------- | | | | 300Hz 1600Hz 3300 4000Hz ``` I bet **engineer\_comp\_geek’s** suggestion of just chopping it off at 300 and 4000 would be a pretty reasonable approximation for most purposes. ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [September 14, 2005, 11:09am UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/11 "2005-09-14T11:09:07Z")
> [@Q.E.D.](#): > > No phones use carbon microphones anymore. I haven’t even _seen_ one in well over 15 years. They almost all use either voice coil or piezoelectric mics these days. They may not be making new telephones with carbon microphones, but there are many old telephones and handsets that are still in service. Telephones used to be designed for a service life of decades. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 14, 2005, 11:17am UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/12 "2005-09-14T11:17:54Z")
I did something like this using Audacity; I actually had to blend some modern recordings in with samples taken from a 1950s cereal commercial (in order to make a radio jingle); I can’t remember the precise order of what I did, but it involved high and low pass filters, downsampling and compressing the dynamic range - all of which have been separately suggested above, but I actually needed all of them in concert. The end result was very convincing - if I still have a copy, I’ll post a link. ---
**Author:** ![picker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/picker/32/13969_2.png) [@picker](https://boards.straightdope.com/u/picker)\ **Post date:** [September 14, 2005, 2:26pm UTC](https://boards.straightdope.com/t/how-to-make-recorded-audio-sound-like-telephone-audio/321506/13 "2005-09-14T14:26:58Z")
Another chiming in for Audacity - I used it to simulate both bullhorns and telephone conversation for a sound design project I was working on. I used the ‘lo-fidelity’ effect, then hi and low pass filters and the result was pretty darn close for a telephone effect. The bullhorn required a bit more finagling, but also worked out in the end.