Spoke Phone allows you to replace all the system prompts and greetings with your own custom recordings, music, and messages. This article will discuss best practices and technical guidance for making your own high-quality audio recordings to upload to Spoke Phone. It contains the following sections:
- Best-practice general guidelines
- Recording using the Spoke Phone app
- Recording using other tools
- Sound quality
Best-practice general guidelines
The key to making a good recording is to limit background noise and provide a script to the person who is recording the message. Whether you are recording via the Spoke Phone app, or using another tool, follow the three best-practice guidelines below:
- Find a quiet place that has no echo.
- Make sure you have a script to follow.
- Practice it a few times to make it natural.
Recording using the Spoke Phone app
You can record a message in your own voice from your Spoke Phone app, and the recording will be added to the audio library so it can be used in the company's Spoke Phone account. Here's what will happen:
- Your administrator will press a button, and you will get a call on your phone.
- You will answer the call and hear a prompt.
- Just follow the instructions.
- You can re-record as many times as you like until you are happy.
- When you are happy, just hang up.
Recording using other tools
You can use any application to create a recording for Spoke Phone. You should follow the guidelines below in order to ensure high-quality recordings.
Record your source at 44.1kHz or 48Khz sample rate to a 16- or 24-bit mono uncompressed WAV or AIFF file. If available, compressor/limiter and equalization processors can help you get the very best audio quality.
For any audio conversion, start with the best possible source recording. This
means well recorded voice in a room with good acoustics and a professional
quality microphone and preamp. You can achieve the best results with careful
mic placement in close proximity to the the sound source.
For voice, place the mic to below or side of the speaker's mouth in order to
avoid distortion due to plosives. You can also incorporate a pop-filter to
avoid this distortion.
After recording, archive your recordings in that source format. Transcoding to the telephony standard will degrade the audio quality to a large degree, and by keeping a high-quality archive you have the option of reusing the source material.
Use an audio software editing program such as Audacity (a very suitable freeware utility) to trim leading and trailing silence from the recording, to normalize the volume, and to apply an equalization to the source file. If you have recorded in stereo sources, convert these to mono.
Sample rate conversion and transcoding
Keep in mind that there will be unavoidable compression artifacts once the file is transcoded to a global telephony standard of 8-bit uLaw. These will manifest mostly as loss of transient response. Also keep in mind that playback on a mobile device will sound considerably worse than a landline phone, due to additional transcoding to GSM format and the adverse impact of poor cell reception.
When uploading an audio file to Spoke Phone you have a couple of options of handling the sample rate conversion that is part of the overall transcoding of the audio file. Depending on your audio software's capabilities, each option may yield the best results, so it is worthwhile to try each of these:
Test A) Spoke Phone transcoding
Upload your high-quality file to Spoke Phone and let Spoke Phone handle all aspects of the transcoding.
Test B) Transcode your audio file in advance.
If your audio software editor has sample rate convertor and encoding capabilities, this option affords you some degree of control over the final results. Also, the quality of sample rate converters (to go from high-quality 44.1Khz or 48Khz to 8Khz) varies depending on the algorithm they use.
Avoid lossy format conversions
Always use the best source recording and avoid any file format that converts one lossy format to another (ie MP3 to 8-bit uLaw), this will definitely introduce additional artifacts. Also, avoid the temptation to compensate for the limited 8Khz bandwidth by over-emphasizing the higher frequencies in your audio source. This doesn't accomplish much and your results can sound worse - but you can experiment with modest amounts of EQ.
Use an equalizer to roll off low frequencies (under 200hz) to help remove room
background noise, emphasize the 2-3Khz range to improve intelligibility, and
notch out 1.2Khz slightly to smooth out harsh sounding voices.