Product Details and Sound Samples

Speechfilter helps transcribers in three ways:

- it reduces the volume of certain types of background noise in recordings, enabling voices to be more easily heard.

- it boosts volume on quiet recordings. Even with your PCs volume turned to maximum, some recordings are too quiet. Speechfilter can easily boost them further.

- it routes or blocks stereo channels. If one stereo channel of your recordings contains, for example, a time-code track you do not want to hear, Speechfilter can block it for you and route the remaining channel into both your left and right headphones.

Speechfilters are easy to install. Simply unplug your headphones from your PC or cassette player, and plug your Speechfilter in instead. Then plug your headphones or speakers into your Speechfilter's headphone socket. Then connect the Speechfilter's USB cable to a spare USB socket on your PC, to power Speechfilter.

Please note you cannot use a Speechfilter with USB headphones.


Speechfilter's volume-boosting feature works with all analogue and digital recording formats.

Speechfilter's stereo channel routing and blocking feature works with all analogue and digital recording formats.

Speechfilter's background noise reduction feature is NOT effective with some recording types. Generally it works only with recording formats with wide frequency ranges such as cassettes, mp3, wma, mpeg, wmv, flv, etc. It will be ineffective with recording formats that are already optimized for voice such as dss, dvf, msv, gsm, and telephone recordings.

Note that a Speechfilter cannot work miracles with unclear recordings. It cannot make a recording less muffled, and it cannot reduce the volume of any background noise that is on the same frequency as voices. Speechfilters make some difference, but not a vast difference. In general, the worse the recording quality, the more difference a Speechfilter will make.

Please listen carefully to the sound samples below. You will need to listen through your headphones to hear Speechfilter's capabilities to proper effect.


Background noise reduction feature

In the three recordings below, the interview can be heard against different kinds of background noise, and a Speechfilter is being switched on and off every few seconds so that you can hear the contrast. Note that a Speechfilter is designed not to alter the quality of the voice but rather to reduce the background noise. Especially the low and bass-intensive sounds will be reduced in volume by a Speechfilter. Remember that a Speechfilter does not work miracles with poor recordings, and it cannot make a muffled recording clear, but it reduces background noise to some extent, and can reduce the amount of mental effort needed over time to transcribe a low-quality recording.

interview with traffic in background

interview with music in background

interview with cassette hiss in background

Channel-switching feature

The recording on the right is a stereo track with an interview in one channel and a time-code track in the other. As the recording plays, a Speechfilter is being used to switch back and forth between one channel and then the other. Notice that when either channel is selected to play on its own, that channel is then heard in both left and right speakers, not just its original channel. This prevents the awkwardness of having to listen to a track in just the left or right channel.

Volume-boosting feature

The recording on the right is very faint but at intervals is being boosted by a Speechfilter. This is a normal volume-boosting function, but it is useful when a recording is so faint that it can barely be heard even with the original sound source (e.g. PC or cassette player) turned up to full volume. The Speechfilter adds an extra volume-boosting capability that should make even very faint recordings audible.