What Quality Is Best For MP3?

MP3 is one of the most well-known and popular audio formats available, but what quality is best for MP3? You might have experienced that awful moment when trying to listen to your favorite song, or you need a specific audio file for work, only to find that it’s badly distorted and the audio quality is too poor to use. We have you covered if you’d like to find out more to prevent future incidents.

The best quality MP3 has a bit rate of 320 kbps; however, 128 kbps produces suitable audio quality and is more popular/common. MP3s are “lossy format” audio files, and while they do not produce the best quality sound, they are small in size, improving storage and transferring rates.

Although MP3 files stifle audio sound quality by virtue of their nature, sound quality is a far more involved process that relates to how the original sound was converted into a binary format. This article investigates MP3 audio quality and basic elements of sound conversion and how they influence quality.

What Determines The Sound Quality Of A MP3

Although the sound file we play on a computer, cellular phone, or other devices might be in MP3 (MPEG-1 or MPEG-2 Audio Layer 3) format, it underwent a small “odyssey” to arrive as an MP3.

The phenomenon of sound quality begins far earlier in the process than in the MP3 format. Rather, it begins by converting an analog (continuous) audio signal to a series of digital (binary) data points.

However, the type of format/encoding on the data is also important, and unfortunately, MP3s are not top of the range, as we shall investigate below.

Bit Rate Is A Cornerstone To MP3 Sound Quality

Bite rate relates to how quickly a device converts digital data into an audio signal. A higher bit rate means more data travels “quicker,” and the audio quality increases accordingly. The bit rate is measured in kilobytes per second.

Low bit rate acts as a type of “brake” bottlenecking sound quality. Although the audio quality might be fantastic on the input side and during the analog-to-digital conversion, if the bit rate is poor, it will reduce the sound quality significantly.

Although 320kbps is the maximum for MP3s, a suitable bit rate is from 96kbps up. Some common bit rates include:

  • 128 kbps (the most common bit rate)
  • 160 kbps
  • 192 kbps
  • 256 kbps

Spotify streaming services use bit rates of between 96 and 160 kbps.

While more usually means better quality (holding more information and less file compression), it is not always necessary. Some devices cannot use the full extent of the 320 kbps bit rate, which means that anything over what is needed is “wasted.”

For example, podcasts only require a bit rate of roughly 96 kbps to produce audible, good-quality sound (podcasts that consist of talking can have bit rates as low as 64 kbps).

The complexity of what you’re listening to determines your bit rate requirements:

  • Enhanced music (like orchestral or high quality) should have a minimum of 128 kbps.
  • Standard music (less complicated/fewer instruments or standard quality) requires at least 96 kbps.

320 Kbps Vs. 128 Kbps, What We Lose, Gain, And What’s Best

Although 128kbps is feasible, and most websites use this bit rate, there is a noticeable drop in quality, particularly if a professional musician or sound producer listens to the track.

The trebles are often lost at 128kbps, and the background “noise” is usually cut. 128kbps is often called “radio” quality, and while you’ll hear the audio clearly, it might not be the best experience.

When an MP3 audio file plays at 320 kbps, it performs at its peak. Three hundred twenty kbps does not cut out as much of the background audio, it keeps many of the higher frequencies, and the sound feels “fuller” overall.

Professional musicians, producers, and singers appreciate this level, as there are fewer emissions from the source file.

However, most audio devices (speakers and headphones) cannot use 320 kbps, so the extra processing power does nothing, and professionals wouldn’t use MP3s other than for casual listening.

These higher bit rate files also require more storage space, defeating the purpose of a smaller file (easier to download and easier to store).

Variable Bit Rate

As technology advances, the world of audio file converters also benefits. Converters can use fixed bit rates or variable bit rates.

As their name implies, fixed bit rates are set at a constant speed and do not change throughout the file.

Variable bit rates fluctuate in their speed. The bit rate will decrease during “quieter” and less “complex” audio segments. However, the bit rate climbs accordingly when the data becomes more complex.

This method allows a healthy balance between file size and audio/sound quality.

Although the bit rate is essential to sound quality, how an analog-to-digital converter captures and converts the signal is of utmost importance.

The Process Of Audio Conversion From Analog To Digital

Computers cannot process sound like our ears do (as a continuous wave). Instead, the computer/device must convert the soundwave into a binary sequence. Most devices use an analog-to-digital converter to accomplish this.

A sound wave enters the device through a microphone, which relays the wave to the converter by activating transducers, which vibrate and generate electric signals (voltage and current).

These signals proceed to the analog-to-digital converter (ADC), which converts the continuous wave into a series of distinct binary words (bytes).

For example, if we think of a graphical representation of an audio wave, we’ll see that the amplitude (loudness) of the wave is on the y-axis, while the x-axis is time. The curve moves to peak amplitude and then drops below the x-axis to the same displacement on the y-axis (in the “negative” quadrant).

The wave then comes up and continues making various patterns.

The AD converter “samples” the audio wave. At fixed times, the converter records the y-value (amplitude). This y-value correlates with binary bytes (zeros and ones). Depending on the resolution, the data points might not fall directly on a whole value (on the y-axis) when the converter takes a sample.

If the reading falls between two numbers, the converter rounds up or down, respectively.

The converter takes these y-value binary points and puts them in chronological order, creating a sequence and converting the analog signal into digital data. This process is called quantization, and the data is uncompressed in the form of pulse-code modulation (PCM).

The converter may compress and encode the data for specific purposes or remain uncompressed.

From Digital Back Into An Analog Audio Signal

When the device “plays” the audio file, it needs to convert it back into an analog (continuous) audio signal.

The device uses a digital-to-analog converter (DAC). These converters take digital information (binary code) and recreate the analog curve through an electrical wave. The DAC reads the binary information and plots the points on the graph, leading to the correct audio wave.

Sample Rate And Bit Depth Are Essential For Audio Conversions

The audio conversion quality is directly related to bit depth and sample rate.

Audio Bit Depth

Bit depth relates to the level of detail on the y-axis during the sampling that an analog-to-digital converter makes.

The greater the bit depth, the more detailed the information and the less the copy deviates from the original soundwave. Three commonly used bit rates include 8, 16, and 24 bits.

A computer’s language is binary, which consists of zeros and ones in specific combinations. Making one byte takes 8 zeros and ones (called bits). Two bytes equates to 16 ones and zeros in combination, and 24 zeros and ones produce 3 bytes. A digital word consists of one or more bytes.

  • 8-bits has the potential for 256 one and zero (binary) combinations.
  • 16-bits has the potential for 65 536 binary combinations
  • 24-bits has the potential for 16.7 million binary combinations.

The bit depth during an audio wave conversion relates to how many bits, and bytes are on the y-axis. A greater bit depth equals more bits and bytes on the y-axis, which allows the converter to take a more accurate “snapshot” of the audio wave with less rounding up and down required.

Lower bit rates, conversely, produce poorer quality pulse-code modulations (among other formats) as they take a less detailed snapshot of the original sound wave. The DA converter must fill these information gaps when transforming the digital code into an audio wave.

Audio Sample Rate

The sample rate relates to the number of samples taken per second. The sample rate is measured in hertz or kilohertz.

Audio sample rate, or sample frequency, relates to how often the converter samples the analog wave. The more samples, the better the sound quality, as there is less information emitted and, therefore, less information that the computer needs to “fill in” during the reconstruction of the wave (DAC).

The standard audio sample rate is usually around 44.1 kHz, which means that every second there are 44 100 samples taken. This rate allows the converter to take enough samples of the sound wave to reconstruct it accurately.

While many MP3 files use 44.1 kHz, some MP3 files (like podcasts) are alright at 22.05 kHz.

 

A higher sample rate and greater bit depth allow the converter to accurately represent the original wave, i.e., a higher-resolution converter.

How The Conversion Process Affects MP3 And Sound Quality

Analog-to-digital conversions are quintessential to sound quality. Low-resolution converters capture less of the original sound wave, so when the digital-to-analog converter changes the CPM into a sound wave, it needs to figure out what’s missing (interpolation).

MP3s are compressed files, meaning they already “lose” some of the original soundwave. If the ADC produces an inferior digital sequence, then the MP3 is further stifled in its quality.

It is best to start with an excellent uncompressed binary sequence from which the MP3 converter can effectively work.

Why Is An MP3’s Sound Quality Not So Great?

MPEG-1 (or MPEG-2) Audio Layer-3 (MP3s) are a type of audio file compressed through a standard compressing and encoding program.

MP3s are regarded as “poor” quality audio files as they are compressed lossy audio files.

Lossy Vs. Lossless Vs. Uncompressed Audio Files

These are the three categories of audio file conversions.

Lossy Audio Files

These files are usually the smallest audio files. The data is cut to compress these files to their diminutive size. During the conversion, the algorithm identifies unnecessary segments of the wave and cuts those out.

Unfortunately, these files tend to have poorer quality audio output due to the cutting (the information cannot be returned). MP3s and AACs are examples of lossy audio files.

During compression, MP3s may lose as much as 90% of the original data. This “sound loss” is usually frequencies humans cannot hear and background noises.

Lossless Audio Files

These files are also compressed but in such a way as to better preserve the audio wave. The program removes redundant information to reduce the file size. Intelligent algorithms scan the data and identify redundancies.

These files are larger than lossy and produce better-quality audio output. Examples of this type of conversion are FLAC, WMA, and ALAC for audio; and ZIP (general).

Uncompressed Audio Files

These are the largest audio data files and closely resemble the original sound wave in quality and content. These files do not undergo compression, so nothing is lost along the way.

These files are the “building blocks” from which the audio file converters pick and choose what to convert.

Examples of this format include AIFF, PCM, and WAV.

Why Are MP3s Popular If They Have Such Low-Quality Audio?

MP3s first appeared in 1993. During that time, these audio files were considerably smaller than WAV and AIF files (or AIFF for Mac users), which were uncompressed.

During the early 90s, file storage on hard drives was an issue, so the minute sizes (1/10 of the other files) of the MP3s made them a practical solution to the space problem.

Although MP3s compressed audio files, they maintained good quality-to-compression ratios (at 16 bits), particularly compared to the CDs available at the time. The internet became more widely available, and soon audio files were uploaded and downloaded worldwide.

The small size and good quality of MP3s made them quickly the preferred choice for online use.

Over time new methods and formats for storing audio came on the market, but MP3s had firmly established themselves in many industries, which is why, 30 years later, MP3s are still some of the most popular audio files.

The Pros And Cons Of An MP3 As An Audio File

While MP3s have some significant drawbacks, that is not to say that MP3s are without some good virtues.

The Positives Of The MP3 File Format

  • At higher bit rate levels (and better sample rates), MP3s are comparable in audio quality to lossless formats to such a degree that untrained (and most) ears won’t tell the difference.
  • Thanks to compression and encoding, MP3 files aresmall, making them ideal for transfer, transport, and storage.
  • MP3s are compatible with most devices and audio players, making them popular and widespread.

The Short Fallings Of The MP3 File Format?

  • At lower bit rates (and with poor sample levels), MP3 file quality falls off compared to other file formats.
  • MP3s are lossy-type files, limiting their capacity to replicate the original sound file/wave. It also means that you cannot convert an MP3 into a lossless, lossy, or uncompressed audio file because of the “cut” information.
  • During the compressing process, MP3 files risk acquiring “compression artifacts” or other “noises” that the original did not have. For example, squeezing an object may distort it; unfortunately, something similar occurs under compression and “cutting.”

What Is The Worst Playable MP3 Quality?

While the bit rate can approach 0 kbps, the lowest recommended bit rate for an MP3 is 128 kbps (for music). At the same time, 96 kbps is sufficient for Podcasts and talking.

While you can cram more audio files onto your device, the audio quality will take a significant blow. If space is a limiting issue, then 128 kbps is the right choice.

Although 128kbps is “playable,” if you want/need sound files that are slightly better but don’t need “top shelf” quality, 256 kbps would serve you better.

256kbps balances smaller file sizes with significantly improved audio quality (and a reprieve for your ears).

Conclusion

While 320 kbps is the best quality speed for an MP3, it is not always the most used. Most standard headphones or speakers cannot process/accommodate this bit rate, so the standard 128 kbps is often sufficient.

While bit rate is essential for MP3 quality, the bit depth and sample rate during analog-to-digital conversion are also fundamental. Although MP3s are not the best quality formats, they are beneficial for storage and transferring, thanks to their smaller size.

References

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