What are the Best Types of Audio Recordings for Transcription?

Do you need audio recording transcription services? Any type of audio recording can be transcribed. However, not all file types are created equal.

Some audio files are easier to send, receive, and play. And since we started this business in 2010, we’ve realized that some files are clearer, and some take up less disk space at the expense of lowered quality. If you are considering purchasing a recording device, you need to know what file type the audio files are recorded, as they may greatly impact your preferred quality. 

If you want to send your files to an audio recording transcription services company, knowing what audio file type your sound files are in will help the file transfer process go much smoother. Today, we’ll discuss the different standard audio file formats, along with a few lesser-known file types.

Waveform Audio File Format (.wav)

The Waveform Audio File Format, commonly known as .wav, is the gold standard in audio file formats. The format is very accessible — it is easy to download and access. Furthermore, the file format is compatible with most, if not all, of the available media players in the market. It is used in professional audio applications, such as music production, sound editing, and audio archiving. Furthermore, .wav files can store audio in various formats, including uncompressed (PCM) and compressed formats like Microsoft ADPCM and GSM 6.10.

One of the best features of the file type is that they are lossless, meaning the audio quality is preserved just as the recording device captured it. As a result, .wav files are perfect for sensitive transcription jobs like law enforcement and court cases. No compression is done, and that means that .wav files have higher bitrates, which can take up much more disk space than other formats. 

File transfer processes that have capped file sizes, like emails, typically cannot handle .wav file transfers. However, they can be saved on CDs or flash drives. Some transcription service providers have secure sites to accommodate the upload and transfer of .wav files. 

MPEG-1 Audio Layer 3 (.mp3)

MPEG-1 Audio Layer 3, or .mp3, is another common file format used for audio recording. The .mp3 format is part of the MPEG-1 standards and builds upon its functionality by compression audio files while maintaining reasonable quality. Reasonable quality can be relative, though, as we need to consider the original file’s recording quality. The file type is usually smaller than .wav as it discards some audio data considered less essential for human perception. Once cut out of the file, the data is lost, known as lossy compression, which can be adjusted, resulting in better audio quality at the cost of bigger file sizes. 

That said, .mp3 files are very popular, especially when sharing smaller files like music and other sound bites. They are easy to download and occupy little space, making them ideal for music players and other recording devices.

However, the file type might not be the best option for those looking to get the best quality of their recorded audio files for transcription, as it may impact transcription accuracy

Advanced Audio Coding (.aac)

AAC stands for Advanced Audio Coding and is a standardized audio compression format designed to produce high-quality audio while maintaining relatively small file sizes. .aac files have better compression, meaning they can maintain audio quality and fidelity better than .mp3 files at lower bitrates and minimal space requirements. Advanced Audio Codic was built upon the MPEG-2 and MPEG-4 standards, making it the successor to the .mp3 file format. 

The .aac file format inherits .mp3’s broad compatibility and accessibility. The file type supports different profiles and levels, allowing for flexibility, and these different profiles offer various features and capabilities, such as support for multichannel audio, higher bitrates, etc. This means that .aac can also be used for high-quality audio recording, making it great for recording audio files for later transcription. Notably, .aac is the default audio format for iTunes, iPhones, and other Apple devices. 

Windows Media Audio (.wma)

The .wma file format stands for Windows Media Audio and was developed by Microsoft as part of the Windows Media framework. Windows Media Audio is designed to compete with other popular audio formats like MP3 and AAC. 

The Windows Media Audio format uses the same compression algorithm as .mp3, which means that any data compressed or cut out is deleted permanently. Microsoft launched the file with compatibility with its product lines in mind; however, it has not reached the same widespread use as .mp3 files, although we’ve seen increasing use over the years. .wma files are even smaller and more compressed than .mp3s, which makes them another good option if uploading/downloading time is of concern. However, the format does offer the same balance by allowing the adjustment of bitrates over disk space. There are different versions of .wav files, such as WMA Pro, which allows higher-quality audio using higher bitrates, and WMA Lossless, which functions like a .wav file with no compression. 

Though not always the case, .wma files are often incompatible with non-Windows-based computers or non-Microsoft devices and programs. The Windows Media Audio format also supports Digital Rights Management (DRM), which gives providers enhanced access to their audio files and allows them to limit playback and block copying, among other things. The adjustable audio quality and relatively small file sizes might be a valid choice for businesses looking to have their audio recordings transcribed, especially if time and disk space are important considerations.

Free Lossless Audio Codec (.flac)

FLAC is a lossless compression format that reduces audio file size without sacrificing original audio quality. This makes it a preferred format for audiophiles and those who want to preserve the highest possible audio fidelity. .flac is an open-source audio compression codec widely supported by major platforms. Another benefit of using .flac is its ability to carry metadata, allowing more file organization options. However, this functionality stores artist names, album titles, track titles, and other data. As far as transcription is concerned, .flac files offer little benefits over other lossless compression formats like .wav and .wma.

Lesser-used File Types

The widespread use of audio files has led to the development of different file types and formats. However, some of these formats may not be as widely compatible as the ones we’ve previously discussed. 

OGG Vorbis (.ogg)

The OGG Container refers to the free, open-container format developed by the Xiph.Org Foundation that can be used for various types of media data, including audio and video streams. Meanwhile, The Vorbis Codec is the standalone compression standard typically used with OGG standard. This means that audio files compressed using the Vorbis Codec result in .ogg files. Compared to .mp3 files, .ogg files are smaller with lower bitrates while maintaining quality. 

Musical Instrument Digital Interface (.midi)

MIDI (Musical Instrument Digital Interface) files don’t contain actual audio data. Instead, they consist of instructions that tell synthesizers or MIDI-compatible devices how to produce music. In short, MIDI files are sets of commands for musical instruments to play, which makes them incompatible with audio recording for transcription purposes. 

Audio Interchange File Format (.aif / .aifc / .aiff)

AIFF is an uncompressed audio file format, meaning it retains the total quality of the original audio recording like a .wav file. Apple Inc. developed the AIFF format for storing high-quality audio on Macintosh and other Apple platforms. Despite that, the format can be used in Windows systems. 

Sun Audio File Format (.au / .snd / .ulaw)

.au, which simply stands for “audio,” is a file format developed by Sun Microsystems. As the name suggests, .au is a simple, common, uncompressed audio format mostly used in Unix- or Linux-based operating systems. Some programs on Microsoft platforms can also open .au files. 

Digital Recorder-Specific Files

Many digital audio recorders also have their specific file formats. Olympus digital audio recorders use the company’s proprietary Digital Speech Standard files in their devices, and file extensions for those files are typically .dss. DSS is commonly used in professional settings where transcription services are involved, and some transcription software supports DSS files directly. DSS uses high compression, meaning smaller file sizes but commensurately lower audio quality. 

Then there are.dct files, which several different brands of audio recorders utilize. Any audio recording transcription services company should be able to accommodate these files easily.


Transcription service providers often accommodate a wide variety of file formats and there are several ways to convert files into more common extensions. However, the best way to ensure fast and efficient transcription is to contact the company and inquire if your file format is supported. 

Ditto Transcripts is a Denver, Colorado transcription company that provides fast, accurate and reliable audio recording transcription services for individuals and companies of all sizes. Call (720) 287-3710 today for a free quote, and ask about our free five-day trial.

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