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■ Common noise removal cases and improvement difficulty

-Voice memo, voice recorder, IC recorder-

The sound of the voice memo (IC recorder) is too quiet to hear


I intended to record an important conversation, but the volume is too low to hear the content .
There are many such consultations for the sound quality improvement service that I run.

For example, such a location

Hidden recording in the room | The distance from the microphone to the conversation is far

Sound quality improvement difficulty ★★★★★

If the distance from the microphone to the conversation is long, the volume is low and the sound of the room is added, making it difficult to hear detailed contents .

Mobile voice memo apps and IC recorders are only intended to be placed on a desk for recording, such as in negotiations. (IPhone also has the ability to adapt to loud scenes such as live performances)


It's just my feeling, but a distance of about 1 meter from the microphone (smartphone or IC recorder) is appropriate for recording a clear conversation.

<Case> Hidden recording in the room

As mentioned above, the proper distance to record a clear conversation is meters. If you put it in a bookshelf or locker in the room, you cannot make a decent recording so that you can hear the conversation accurately later.


There are many cases where couples who are arguing for divorce, bullying at work, and those who are suffering from power harassment record in such places.

If the distance to the conversation party is long, it is necessary to record uncompressed with a linear PCM recorder equipped with a high-sensitivity microphone for recording musical instrument performances. (* We do not recommend secret photography)

<Case> Recording minutes in a large conference room

Recordings in the conference room may be difficult to hear depending on the standing position, depending on the position of the microphone and the position of the speaker.


Even in such a case, if you do not use a linear PCM recorder with a built-in stereo condenser microphone that has high sensitivity and wide directivity, the sound quality that is easy to translate is difficult.

I put it in my bag or bag

Improvement difficulty ★★★★


If you put the recorder in your bag, it will block the direct sound, and the sound will be trapped. It is difficult to improve later because the quality when collecting the sound from the microphone deteriorates.


If you put the recorder in your bag, it will block the direct sound, and the sound will be trapped. In addition, strong bass noise such as surrounding footsteps tends to enter the feet, so the quality tends to be even more severe.

You can expect a little if it is close to the mouth of the conversation or in a quiet place where there is almost no surrounding sound. The closer you are to the sound you want to record, the better the resolution of the microphone.

Improved accuracy that depends on the recording resolution

* The sound quality improvement effect is completely different between the one recorded by the wav (uncompressed) method and the MP3 (compressed sound source). Long time mode is mp3 on many recorders.

Since MP3 has a large amount of data thinned out due to capacity reduction, the accuracy is considerably lower than that of an uncompressed sound source when improving after recording.


Telephone (voice of the other party over the handset)

Sound quality improvement difficulty ★★★★★


There seems to be an opportunity to record the voice of the other party over the telephone when dealing with complaints or disputes in court.
Unless you use a dedicated app conversation or a phone with a recording function, the conversation you hear from the handset is a small mosquito-crying sound. There are also regular requests to make this sound louder .


Telephone conversations have a large volume difference from the voice of the person recording the voice compared to the crying voice of the other party's mosquito, so in many cases it is necessary to make fine adjustments for each conversation phrase. There is a huge amount of work. Since the difficulty of improvement is high, there are many cases of giving up.

Difficult to recover small phone sounds
  • Make a small mosquito-like voice louder →

  • Reduce the loud voice of the recorder on the front side → Mend

  • Selection of the part where the conversation crosses → Judge is difficult


We introduced examples of users who have problems with voice memos and data recorded on recorders that are too low to hear, and the difficulty of improvement. Since most improved degree of difficulty is high, adopted probability If you have Welcome the person who worries in not high, but the same state hybrid sound reform you feel free to contact us please.

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