There are many options for Police Interview Room recording systems – for both forensic interview rooms and witness/suspect recording rooms. Today we are going to dive a little deeper into microphone options and designs to best capture accurate and clear voices. Here we see some of the basic voice pick-up patterns of most standard microphones.
Omni directional mics are designed to pick up sound from any direction. In interview room recording, this often means that it’s also picking up audio from outside the room. The Unidirectional mics with a Cardioid pickup pattern is best for forensic interviews as it can be aimed at the interviewer and interviewee. Bi-directional mics are not common interview room microphones.
Typical interview rooms tend to be small and the subjects physically near each other. Each of these microphone types can do a good job capturing interviews but there are other factors that improve audio quality even further.
The audio industry is replete with lower end mics that are perfectly serviceable in most standard applications. However, police interview rooms are not most applications. Recording voices is tested by emotion, soft speaking, whispering, and even with the hands over the face. Add to the equation outside factors such as heating and cooling fan noise, buzzing fluorescent lights or people working in close proximity and you can quickly see that capturing every word can be a challenge.
Toward that end Precise Digital has partnered with a microphone manufacturer to focus on 4 variables we can control: Gain, Volume and Noise Filtering (reducing fan noise), and placement.
Both gain and volume levels refer to the loudness of the audio. However, gain is the input level of the audio and volume is the output.
In recording audio, gain is the first control we adjust on the microphone signal to make sure the audio levels are loud enough, but not too loud to cause distortion, to be recorded. Once we have the proper input gain set we can adjust the volume levels after that. All our forensic interview microphones have a gain control built into the mic and a volume adjustment built into the amplifier.
When replacing a customer’s existing interview room recording system the number one complaint we hear is that the audio quality is just bad. Over 90% of the microphones we’ve replaced have no such controls.
The volume is set at the amplifier to simply allow us to hear the interviewer and interviewee louder. Our recordings are played back on anything from simple laptop speakers to TV’s with sound bars, so we have developed a control to adsorb the louder voices. Every interview recording system should have these basic elements – most don’t.
How About Even Better Microphones?
What if we could design a microphone that was designed to ONLY pick up human voices? There is no magic bullet…a microphones job is to pick up sound. We can’t tell it to ignore the people talking in the hall whose voices are bleeding through the door into the interview room – but we can mitigate extraneous sounds by filtering out frequency ranges outside those of the human voice (see chart). This is a great breakthrough in audio quality and really improves the ability to capture audio from whispering kids to people talking into their hands. We would be happy to send you a sample recording.
The last element of interview recording microphones is often overlooked. With microphones, you want them to be as close the subject as possible so mic placement is important.
Many of the existing microphones we replace are ceiling mounted. If you look around you may have seen them. It’s no wonder the audio quality is poor with the rushing sound of the air coming from the air vents and the lights buzzing.
Precise Digital has developed the low noise, adjustable gain microphone and amp that are covert and vandal resistant so we can position closer to the subjects. Attention to how close we can get the mic without being intrusive can help you win the audio recording game.
As always – Precise Digital is your source for quality interview recording.