File format, editing and optimisation of recording quality

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Table of contents of this article

File format and conversion

Preparation of the transcription

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After the interviews have been conducted and recorded, whether as a video or audio file, a not inconsiderable intermediate step is required for the subsequent evaluation: the Transcription. This generally refers to the transcription of the speech from the audio or video files into written form. This step should not be underestimated, as a transcript is the prerequisite for a high-quality and detailed analysis and can be very time-consuming without specialist knowledge.

With the transcription, the orally interviews are transcribed into written written form - this is a prerequisite for documentation and analysis.

Accordingly, there are a few points to consider when transcribing. These are explained in more detail below.

File editing

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The starting point of any transcription is always the recording file of the interview. Consequently, it is particularly important to save it externally, preferably immediately after the interview, and to transcribe it accordingly. prepare. This includes, among other things, converting it into a suitable format. Some transcription or analysis procedures also require special formatting of the documents.

For a transcription, files may have to be files may need to be prepared - this can be a conversion of the of the recording or a special formatting.

File formats and conversion

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In order to be able to use an audio file appropriately, one should always pay attention to the corresponding file format. Not all programmes support every format. The individual formats also have different advantages and disadvantages.

One of the best-known audio formats is MP3. It is characterised by very high quality and low memory requirements. In addition, it can be recognised and processed by the majority of programmes and systems. Consequently, it is always a good and safe choice to choose the MP3 format for your recordings.

The MP3 format should be should be preferred - it is very high quality with low low storage requirements.

An alternative to this is the WAV formatwhich offers a somewhat higher quality, but has an enormously large memory requirement. One should only opt for WAV if the files are not to be transferred.

An alternative is the WMA audio format which also offers high quality. This format has the advantage that the file size is comparatively small. However, this format is mostly only supported by Windows operating systems, which may limit its further use.

The WAV format has an enormously large storage requirements - only if high audio quality is important quality is important, it should be chosen. For this the WMA format is also suitable with comparatively less storage requirements.

The alternative of Microsoft's competitor Apple is the M4A format. This is encoded either in the AAC process or by the Apple Lossless process. The former results in a lossy conversion and the latter ensures that the original audio quality is preserved. The AAC format offers a comparatively small file size with high quality. The disadvantage of Apple's formats is that many other manufacturers do not offer a support function.

M4A is Apple's alternative format - which offers a comparatively small file size with high quality. Disadvantage: The formats are not not supported by many programmes.

In addition, audio files can of course also be saved on a stick or a CD, although the storage space is limited. For further processing of the files, e.g. in the form of a transcription, the data must also be copied to the PC in a cumbersome manner. If the audio files are nevertheless available in this format, the infobox below provides instructions for transferring them to the computer:

Rip and convert CDs with Windows Media Player

  1. Insert the music CD into the CD drive of the PC.
    Copy files from the CD to the PC
  2. A programme (e.g. VLC Media Player, iTunes, ...) opens
  3. Close the programme, press the Windows key and "R" at the same time.
    Window with "Run" opens
  4. Enter "wmplayer.exe" in this window and click "ok".
  5. Windows Media Player opens and the CD including the title is displayed
  6. There is a box with a tick in front of each title
    Remove the tick from the titles that are not to be copied.
  7. Click on "Copy CD" in the menu bar (this can take up to ten minutes for normal CDs).
  8. The CD with the copied tracks is now in the "Music" folder
  9. The files are in WMA format
    WMA format of the files can be converted if required (see below).


Transferring CDs with an Apple Mac computer

Converting the files via iTunes (The audio track must be available in the iTunes library)

  • Conversion of the files via iTunes
    (The audio track must be available in the iTunes library)
  • Settings General Import settings Import with Select encoding format Select one or more music titles File Convert Create [Format] version

Finally, it is important to note that all formats can be converted into the desired format. Among other things, this can be done online via the browser using a service such as:

For many conversion processes, if a larger range of functions is desired or if there are data protection concerns (with the above-mentioned provider, it is necessary to upload the files to the provider's servers), it is advisable to use a special Conversion programme. This includes, for example, the Free Audio Converter. The test version is available online as a free download. The AVS Audio Converter is also recommended as a free demo version. The Switch Audio Converter is a high-quality - but not free - alternative. There is a one-time licence fee of €17 for using the programme (as of 12.11.2019), but for this you get many functions and compatibility with almost all audio formats.

For the conversion we recommend special programmes - free free programmes are the Free Audio Converter and the AVS Audio Converter, and the paid functions are offered by the Switch Audio Converter.

Transferring recordings to the PC

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After recording, the recording must be transferred to the PC so that it can be further processed. This is where questions and difficulties often arise. Of course, the procedure always depends on the particular device with which the recording was made.

Minidisc recorder or tape cassette
With these two devices, transferring the files to the PC is somewhat complicated because they are analogue devices. Nevertheless, digitising the recordings is possible with a little effort:

  1. Connect the minidisc recorder or tape recorder to the PC via audio cable (microphone input or line-in input).
  2. Start the corresponding programme, e.g. Audiograbber or Audacity.
  3. Make the necessary settings (Audacity: Edit Settings Devices Recordings)
  4. Start the recorder and record on the PC at the same time (by pressing "Record"). If the audio quality is poor, adjust the sound settings on the recorder or Windows if necessary.
  5. Save or export file

Digital recorders
With digital devices, transferring the recordings is much easier:

  1. Connect the recorder to the PC using the USB cable.
  2. Copy the file to the PC via Plug and Play (the dictation machine appears in the system as a normal removable medium, just like a USB stick, for example).

With some devices, there is also the option of sending the recording directly from the device by email or transferring it to the cloud. This further simplifies the transfer.

Mobile devices (smartphone or tablet)
For mobile devices, the procedure is similar to that for digital recording devices.

Simply connect the mobile device to the PC via USB

Copy the files to the PC (the mobile device appears as a removable storage medium; if necessary, refer to the operating instructions of the device)

Alternatively, the file can also be transferred wirelessly. Due to the file size, sending longer recordings by e-mail is usually not possible. Instead, free file hosting services such as WeTransfer can be used instead. To do this, simply install the app, which is available for both Android and iOS, on the smartphone, upload the file and finally download it again on the PC via the browser by clicking on the link from the email. Any data protection concerns must be taken into account here, as the files are temporarily stored on WeTransfer's servers.

For the transfer of larger files, you can use file-shooting services such as WeTransfer or cloud services such as Dropbox, Google Google Drive or OneDrive can be can be used.

The same procedure can also be used with the various cloud services, such as Dropbox, Google Drive or OneDrive from Microsoft. For this purpose, the corresponding apps can also be installed on the smartphone.

If temporary storage of files on external servers is not desired, there are now also some apps that enable wireless file transfer between PC and smartphone via WLAN, e.g. WiFi File Transfer. In this case, no data is stored on external servers, but the PC and the smartphone must be connected to the same WLAN.

Wifi File Transfer enables a transfer via WLAN - advantage: The files do not have to be on an external server be temporarily stored on an external server.

In any case, it is always important to archive and back up the recordings as soon as possible so that no data is lost. The file should therefore be saved either in the cloud or on a CD or an external hard drive as a backup.

Tips for naming files

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Another aspect is the correct naming of the audio files. If done incorrectly, this can lead to major problems in the further workflow, but is often neglected.

After the interviews have been conducted, they are usually instinctively named very similarly (e.g. Interview 1, Interview 2, Interview 3 etc.), or the same name is even chosen for all files. This makes working with the files immensely difficult - not only in the context of transcription, but also in relation to the entire work process - if, for example, a specific passage from an interview is to be listened to in the later course of the analysis.

To avoid this, the naming of the audio files should be as simple and unambiguous as possible. Generally, file names that contain letters instead of numbers are easier to find. If you want to limit yourself to numbers, always use the format year/month/day (yyyy:mm:dd) (e.g. "20180415"). This will automatically sort the files chronologically.

However, one should be aware that the exclusive use of numbers for file naming may be insufficient. For the best Clarity a combination of date and a proper name or an abbreviation of the proper name should be chosen. This abbreviation should refer to the processor, interviewer or interviewee.

The files should be named simply yet unambiguous names, so that they can be easily identification at all times.

Cutting programmes

Editing audio and video

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The next important point in interview processing is editing. Many interviews contain passages that are irrelevant for the analysis and are accordingly not transcribed (e.g. small talk at the beginning or interruptions in the interview). It can also happen that the interviewee asks for particularly sensitive passages to be deleted. These are therefore not available for evaluation and should be cut out of the audio file/recording.

Cutting a file also makes transcription easier on the one hand, since the audio file only contains the parts to be transcribed, and on the other hand it also makes it easier to find the relevant parts of the interview.

A free programme that is very suitable for this purpose is Audacitywhich is presented in the following chapter. At this point, we will only briefly discuss the functionality of the programme with regard to editing audio files.

In some cases it makes sense to cut the recording the recording to remove unwanted unwanted passages - a free free programme for this is Audacity.

There are three points you should always of audio should always be kept in mind:

  1. It is always advisable to wear headphones to be able to concentrate better on individual passages 
  2. It should be checked exactly which passages can be removed. For this purpose, Audacity has the zoom function, whereby one can always orientate oneself by the wave representation of the volume: If there are no or only very slight waves, then there is probably no speaking at this point. 
  3. In general, it is always important to save the original file as a back-up.

To remove the part, simply mark it with the selection tool and then delete it with the "Remove" button.

If only a longer part is to be cut with Smalltalk at the beginning and otherwise no complicated editing work is necessary, an extensive tool such as Audacity is not absolutely necessary. Instead, simpler programmes can be used here that can be run directly in the browser without downloading. Two of the best options are and With both, only the file is selected and then the area to be cut is captured with two sliders. The sound quality remains unchanged. The disadvantage of these two tools is that only the mp3 format is supported. In addition, data protection concerns can arise here, as the editing process does not take place locally on the PC, but on an external server of the respective provider.

Good alternatives for cutting are cutmp3 and audiotrimmer - These are particularly easy to application.

If a transcription service provider such as is commissioned, there is no need for editing. Here it is sufficient to specify the sections to be transcribed (e.g.: from minute 01:20 - 05:50). Only these will then be taken into account in the transcription. Alternatively, the service provider can also be informed of the passages that are not to be transcribed.

Noise reduction and filtering

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Another important point for a good quality audio recording is to avoid noise during the recording.

A number of measures can be taken in advance to prevent noise measures can be taken in advance to prevent noise such as hissing:

  • Place the microphone close to the speaker. In group discussions, use several microphones if necessary.
  • Quiet environment
  • Avoiding reverberation and other disturbing noises
  • Switching off smartphones (unless used for recording)
  • Immediate enquiry in case of acoustically incomprehensible statements

Despite following these instructions, there can always be problems with the sound quality or similar. In this case, the audio quality can also be improved somewhat afterwards so that all statements are understandable, the background noise is reduced and thus the transcription is made easier.

Audacity can again be used as a tool here:

  1. Open audio file in the programme
  2.  Find a short section in which, if possible, only the noise can be heard, mark this section and go to "Effect" and "Noise reduction" and then: "Create noise profile".
  3. Then mark the whole file or parts with noise and click "Effect" and "Noise reduction" again.
  4. Listen to test
  5. If the result is not yet satisfactory, it can be optimised via the controls "Noise reduction (db)", "Sensitivity" and "Frequency smoothing (bands)".
  6. Applying the filters may take some time (especially with larger files)
  7. In case of hum: Use the equaliser, which displays certain frequency ranges and allows you to remove them. 
  8. Clicks or scratches can be reduced with "Effect": "Click filter". Here you can set various parameters that determine at what volume and length the filters perceive something as a disturbance.

If an interviewee is too quiet, e.g. because he or she is sitting too far away from the microphone, Audacity can also be used to increase the Volume can be increased at the appropriate point. To do this, simply select the envelope curve tool, set a white control point to the left and right of the point and then click exactly on the point where the volume is to be adjusted. This point can then be moved up or down to adjust the volume at that point.

In Audacity you can also adjust the volume - this can be used to adjust softly spoken words can be adjusted. can be adjusted.

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Further questions and answers

✅ What is the best file format for an audio file?

The File formats of audio files differ mainly in terms of file size. If you have a choice, then space-saving file formats such as m4a or mp3 are recommended and the avoidance of very large file formats such as wav.

✅ What is the best file format for a video file?

If good sound and picture quality is important, then a MOV or MPEG file format is recommended, AVI files also have good quality but can become very large. There are many other possible formats, but some of these are not compatible with all players.

✅ How can you improve the quality of an audio file?

For Noise reduction and filtering there are some free programmes like Audacity that give good results. The easiest way, however, is to already have a Good recording ensure that the quality is good from the outset.

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