Why Do WAV Files Sound Better Than MP3?

When looking to maximize audio quality, it is almost always advisable to use WAV instead of MP3. But why, exactly, do WAV files sound better than MP3?

WAV files sound better than MP3 because they contain uncompressed PCM audio data. Unlike WAV, MP3 uses lossy compression to discard inessential signal information. Nonetheless, the average listener usually will struggle to detect the difference in the sound quality of these formats.

The sound quality of audio file formats depends on the methods used to sample or encode input signals. This fact is illustrated clearly by the distinction between WAV and MP3. The following technical information should hopefully assist anyone seeking to understand why WAV sounds better than MP3.

WAV Sounds Better Than MP3 Because It Is Uncompressed

The sound quality of WAV is better than MP3 because it contains uncompressed audio data. This means WAV files retain the full complement of information from the input audio signal.

In contrast, MP3 is a lossy compression format that removes some of the original audio information to reduce the file size. As a result, MP3 produces a less accurate mathematical reproduction of the original audio signal than WAV.

So, when sampling an audio signal in WAV, the newly-created file will sound better than MP3, which loses subtle sound details during the compression process.

While WAV files have higher sound quality than MP3s, it is crucial to emphasize that this difference is generally not significant. Double-blind listening tests demonstrate that people with untrained ears struggle to differentiate between WAV and MP3 files (provided the MP3s are encoded at a high bit rate).

It is critical to note that numerous variables can confound direct comparisons between the quality of MP3 and WAV files. Nonetheless, experts agree that the WAV format produces better audio quality than MP3 because no audio information is lost.

A closer examination of WAV and MP3 will help readers appreciate why the former format sounds better.

WAV: The Format For Maximizing Audio Quality

Waveform Audio File Format (WAV) is a container format created by Microsoft and IBM for storing uncompressed sound data.

 

WAV files generally hold uncompressed linear pulse-code modulation (LPCM) data (but can support compressed audio). LPCM is a form of high-quality audio typically found on compact discs (CDs). The typical parameters for LPCM data sampling are 16 bits at 44.1kHz, recorded to two channels.

The fact that LPCM is uncompressed means the output signal is identical to the input audio signal. LPCM records and digitizes analog signals without losing any original sound information. This means the quality of WAV files is as good (or bad) as the source audio recording.

The WAV format is a specific kind of Resource Interchange File Format (RIFF). RIFF is a container format that breaks audio data into chunks. Each chunk has a 4-character tag that instructs file readers (such as media player programs) how to interpret the data. The tags also contain metadata and chunk sizes.

Tagged container formats like RIFF provide the benefit of being easily extendable with a wide variety of file readers.

Due to the high fidelity of WAV, this format is used widely in professional audio production contexts. Indeed, sound engineers and producers generally favor WAV for sound recording and editing. MP3, in contrast, might only be used to distribute finished tracks.

MP3: The Format For Minimizing Audio File Size

MP3 has been the predominant compression audio format since the 1990s. The format was created through the efforts of computer scientists at the Fraunhofer Society working in collaboration with international colleagues.

Though superseded by the newer, higher-performing Advanced Audio Codec (AAC) format, MP3 is still widely used for encoding, storing, sharing, and playing audio bit streams.

MP3 is a container file and a specific type of coding format. The MP3 container usually holds audio data that has been encoded with an associated MP3 encoder (MPEG-2 or MPEG-1 for older recordings).

MP3 files contain a series of interconnected frames, each with a data block and header. The header provides information like metadata and decoding instructions, while the data blocks consist of compressed audio data.

During the MP3 audio encoding process, a hybrid algorithm performs lossy compression on the data, which reduces original file sizes by roughly 75% to 95%. The application of lossy compression underpins the difference in sound quality between MP3s and WAV files.

Lossy Compression

MP3 is perhaps the most well-known example of lossy compression. This sophisticated encoding method reproduces digital audio signals with significantly less information without reducing the bit depth and rate.

Lossy compression employs a psychoacoustic modeling technique called perceptual coding. This technique exploits limitations in human hearing by selectively removing sounds from the source data that are inaudible to most people.

For instance, perceptual coding discards redundant sounds that are masked by other signals with the same frequency. Similarly, if a loud and soft sound play simultaneously, perceptual coding retains the higher amplitude signal and removes the weaker, masked sound.

MP3 encoding performs lossy compression in the following sequence:

  • input audio data is separated into frames,
  • a modified discrete cosine transform (MDCT) algorithm compresses the frames,
  • a fast Fourier transform algorithm compresses the output further,
  • psychoacoustic modeling removes inessential audio data,
  • the MDCT algorithm compresses the output again,
  • the frames get encoded and formatted.

Though usually understood as a process that loses information, lossy compression enables more efficient replication of audio signals. Lossy compression approximates the input sound with reasonable accuracy but considerably fewer bits of information, dramatically decreasing the file size.

However, lossy compression not only discards a sub-set of the source audio data but also introduces noise artifacts that were not present in the source audio. For this fundamental reason, the sound quality of a lossy format like MP3 is technically inferior to WAV.

WAV Vs MP3: Listening Tests

As an uncompressed format, WAV can potentially contain sounds spanning the full spectrum of frequencies perceptible to the human ear. In contrast, the perceptual coding performed during the MP3 encoding process discards certain sounds at the highest (above 18kHz) and lowest ends of the frequency range.

This means that, at a theoretical level, WAV produces higher-quality sound than MP3. In practice, the distinction between these formats is less apparent.

While most audiophiles and sound engineers hear the difference between WAV and MP3 files, the average listener might find it difficult to differentiate between these formats. Systematic listening tests affirm the difficulty in distinguishing between the sound of MP3 and WAV.

Comparing WAV And MP3: Confounding Variables

The discussion so far has emphasized that WAV sounds better than MP3 but there are myriad variables that can potentially complicate the task of comparing these formats.

These confounding variables determine the ease or difficulty of differentiating between WAV and MP3 files. In principle, it is possible to have an MP3 that sounds better than WAV.

Bit Rate

The bit rate of audio files exerts a fundamental influence on their sound quality. Bit rate refers to the amount of information (or the number of bits) processed within a particular time. This parameter usually gets measured in kilobytes per second (kbp/s).

In the audio file context, the bit rate is the quantity of information transferred per unit of time during playback.
The bit rate of an audio file is selected when encoding input data (in the case of MP3s) or when sampling or recording analog sound signals (as performed with WAV).

Bit Rates Of MP3 And WAV

Direct comparisons between the bit rates of uncompressed and compressed audio files are somewhat deceptive due to the difference in the quantity of audio data. Nevertheless, the central point to appreciate is that the sound quality of audio files generally improves at higher bit rates, assuming all other factors are equal.

WAV files holding LPCM audio have a standard bit rate of 1411.2kbp/s.The format can potentially go as unnecessarily high as 12288kbp/s (with a 192kHz sampling rate, 32-bit depth, and two channels). On the other hand, the bit rate options for the MP3 format range from 32kbp/s to 320kbp/s.

MP3 files with bit rates below 128kbp/s provide low sound quality and are only suitable for speech audio. 192Kbps is generally the minimum bit rate for encoding music in MP3. MP3s sound best when encoded at a bit rate of 320kbp/s (though 256kbp/s is more popular).

So, it is easier to discriminate between a low-bit-rate MP3 and a WAV file. For example, non-expert listeners will easily hear the difference between a WAV file and an MP3 with a bit rate of 32kbp/s or 96kbp/s.

Conversely, an MP3 with a bit rate of 320kbp/s can often sound as good as a WAV file.

Type Of Codec

The codec used to encode audio data into an MP3 container affects the sound quality and therefore influences comparisons with the WAV format.

MPEG-1 And MPEG-2

An MP3 with data encoded with an old, inefficient codec will produce a lower-quality sound that is easier to differentiate from WAV. For instance, the original MPEG-1 codec released in the early 1990s used a rudimentary encoding algorithm that compromised quality for the sake of data compression.

The MPEG-2 audio and video standard introduced a new and improved codec for the MP3 container format. MPEG-2 supports more channels and bit rate options than the MPEG-1 codec, enabling the production of higher-quality audio.

So, it is relatively easy to hear the difference in audio quality between a WAV file and an MP3 encoded by this antiquated MPEG-1 codec. It becomes more challenging to make this distinction when comparing the sound of a WAV file and an MP3 containing sound data encoded by the MPEG-2 codec.

LAME

The most efficient, high-performance codec that is compatible with MP3 is called LAME. First released in 1998, LAME is a free, open-source codec with superior transcoding capability, especially at variable and mid-to-high bit rates.

The high quality of LAME encoding is due to the contribution of software engineering experts from around the world. Unlike other MP3 encoders (which are no longer maintained), LAME continues to evolve and undergo improvements, with engineers increasing the codec’s superiority over older MPEG-1 and MPEG-2 codecs.

There have been multiple iterations of LAME, with each new version offering enhanced levels of performance. The latest and most advanced version is LAME v3.100 (released in 2017).

Consequently, distinguishing between the sound of a LAME-encoded MP3 and a WAV file can be tricky. If the MP3 is encoded with the latest version of LAME, differentiating the file from WAV becomes even more challenging.

Input Audio

The type of sounds represented in the audio data is another variable that affects comparisons between WAV and MP3 formats.

Due to its design and algorithms, the MP3 format produces the best sound quality when representing a small number of acoustic instruments and relatively minimal fluctuations in amplitudes and frequencies. The MP3 format is less suitable for larger, more complex, and dynamic audio, such as orchestral and techno music.   

Encoding high frequencies is another limitation of the MP3 format. Noise artifacts from lossy compression are particularly conspicuous at the top end of the frequency spectrum.

For example, the MP3 format is less capable of cleanly replicating sounds from high-pitched instruments like violins, high hats, cymbals, and claves. The compression noises from these high-frequency audio sources are increasingly noticeable when playing MP3 files at low volume.

At a basic level, the source audio quality directly impacts comparisons between WAV and MP3. An MP3 encoding of clear, high-quality source audio will probably sound better than a WAV file with muddy, low-quality PCM data.

Hardware

The quality of the hardware one uses to listen to MP3 and WAV files also complicates efforts to compare the sound of these different audio file formats. 

The performance of the following physical systems and devices affects the quality of WAV and MP3 files:

  • cables,
  • amplifiers,
  • headphones,
  • speakers,
  • digital-to-analog converters.

Premium quality, high-performance hardware reveals more of the subtle frequencies and dynamics in the audio, while at the same time making noises like compression artifacts more conspicuous.

Conversely, low-quality hardware like cheaply-manufactured headphones decreases the clarity and resolution of the audio, making it difficult (if not impossible) to discern the nuances in the audio.

The implication is that it is more difficult to distinguish between the sound of MP3 and WAV files when listening through low-quality hardware. Hearing the differences between MP3 and WAV is significantly easier when listening via cheap, poor-quality audio playback devices and systems.

Hearing Abilities

The ease or difficulty of perceiving sound quality differences between WAV and MP3 depends on a person’s hearing abilities. Age, health, and listening skill are central factors shaping individual hearing ability.

Age

The capacity of the human auditory system diminishes as people age. As a result, people’s ability to hear finely-grained details in the audio output of MP3 and WAV files decreases.

A reduction in the range of frequencies that older individuals can perceive is a primary change that occurs. In particular, the ability to hear high-end frequencies decreases with age.

As indicated earlier, the noise artifacts from lossy compression are introduced predominantly for high-frequency sounds. This means people with age-related hearing loss will find it more difficult to discriminate between MP3 and WAV files.

Health

Similarly, the general health and condition of a person’s auditory system have a fundamental effect on their ability to distinguish between audio formats.

For instance, having damaged eardrums from prolonged exposure to excessively loud sounds undermines an individual’s ability to differentiate between WAV and MP3 audio files.

Listening Skills

Finally, listening skills determine how readily an individual can hear differences between the sound of MP3 and WAV.

People who play musical instruments for a few years tend to develop finely-honed listening capabilities. Instrument players’ ears become trained over time, enabling them to discern subtle differences between audio formats like MP3 and WAV.

Having a background in professional sound engineering also trains the ear to an above-average level of discernment. Experienced engineers can generally differentiate between lossy and uncompressed formats (like MP3 and WAV).

When To Use WAV And MP3 Files

Making an appropriate choice between WAV and MP3 depends on the situation. Sometimes it is advantageous to use WAV, but there are also scenarios where MP3 is the superior format.

It is most beneficial to use WAV when there is a need for audio with high fidelity and resolution.

This format is ideal for music production and engineering, where quality and the ability to retrieve and manipulate original audio data are priorities. WAV is also the standard format for television, radio, and DVD. These applications require the highest broadcast-quality audio.

MP3 is more useful for storing and disseminating audio on the internet, due to the format’s reduced bandwidth requirements. As compressed files, MP3s are superior to WAV for sharing audio on web pages or online applications like streaming platforms.

Conclusion

WAV files are uncompressed, so they sound better than MP3s. As an uncompressed format, WAV files contain the full complement of input analog waveform information. MP3 files, in contrast, store data encoded through lossy compression, which means a portion of the original audio data is discarded.

While WAV usually has higher audio quality than MP3, the extent of this sound difference depends on multiple factors. These factors include the bit rate, the codec used to encode the MP3, the clarity and complexity of the source audio, the hardware used to play the files, and the hearing abilities of the listeners.

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