I can hear this on high end studio monitors. I took it upon myself to help train his ears, and now, he can also hear the difference and has become just as passionate about the subject as I have. I have to thank him for letting me use that as a primary example. We have gone on to train our ears to hear a lot more things. In order to hear the differences, you need to know what a MP3 sound is, to distingush between an MP3 and the lossless file formats.
Fact 1. Some humans can hear up to 22Khz. Fact 2. Storage is so affordable these days, there is no longer an argument for saving a lower quality file. Fact 3. An MP3 is lossy and compressed. A WAV is lossless and uncompressed. Fact 4.
MP3 and other lossy formats exploit general human hearing to reduce file size. That was the only reason for it to be used, thus causing quality loss. What exactly is the effect of compression on the audio though? Can you just convert to WAV and magically get the quality back? Let's briefly take a look at each of the formats before diving into when to use them. CDs are stored with bit data recorded at Although LPCM data is not compressed, it's quality can be increased by increasing the sampling rate or the bit depth of the recorded data.
Professional musicians will often use 48khz data recorded with bits during the mixing portion of their production. Some will go as high as 96khz, although as you go higher, the quality to size trade-off begins to diminish. In order for you to understand what these numbers mean, let's take a look at what sampling rate and bit depth mean in relation to audio files.
From this information, you can see that a WAV file's size is a product of its sampling rate, bit depth, length, and the number of tracks it contains. Most audio files are mono 1 track or stereo 2 tracks , although surround sound systems can have significantly more tracks of data.
More specifically MP3 is a lossy compression format. This means that data from the audio file is thrown out in order to make the file size smaller. A file format could throw out all of the frequencies in an audio file that the human ear is incapable of perceiving and shrink the file some, but MP3 goes further.
MP3 files rely on something called audio masking. The perception of some frequencies is masked when certain other frequencies are present. This phenomenon was first discovered in , long before computers were even a thing. By getting rid of this data where the human perception is lowered but not eliminated , MP3s can lower the size of the file with a small loss in quality. By changing how much of the data gets eliminated, the trade-off of quality and size can be controlled. MP3 file quality is measured in bitrate.
This is the amount of data that is allowed per second of audio. The smaller the bitrate, the more data must be lost. The files can take advantage of intelligent algorithms that will vary the bitrate as the file is encoded. This means that data can be preserved when deleting it would lower the quality too much, and discarded in the parts of the file that would not suffer as much. Now that we've discussed the formats, which formats when the WAV vs.
MP3 battle and when? WAV files are lossless and uncompressed which means they lose no quality from the original recording. A stereo, CD-quality recording Increasing to 48 KHz and 24 bit stereo will be reflected in a change from 10 Mb per minute to We can now take a closer look at some of the differences between the two.
As I touched on in the overview, lossy compression discards some data from the original recording. The algorithm makes assumptions on what to discard based on frequencies the human ear is unlikely to detect. The perceived frequency range that is audible to the human ear is 20 Hz to 20 kHz. Anything that is unlikely to be detected is filtered out or converted to mono signals to take up less space.
You can see the masking tone creates a wider, masked area. Sounds that are very quiet and masked by much louder sounds are also discarded to save space. The study of how humans perceive sound and a huge part of how lossy compression works. It is argued that our brains cannot accurately perceive every bit of data that passes our ears when listening to CD-quality audio. Artifacts left behind by lossy compression create unwanted sounds or anomalies that are not in the original recording.
These come in many different forms such as loss of bandwidth, pre-echoes, and post-echoes, double-track effect, Dynamics and phase shift and weakened low end.
Now, at kbps, MP3s filter the higher frequencies very crudely, discarding frequency content anywhere above approx. The iTunes MP3 encoder goes as far as creating distortions in this frequency range so in order to maintain full bandwidth through the iTunes MP3 encoder you must have a bit rate of kbps or higher.
Even if the quiet one happens first it will be masked by the louder one if there is only a small interval of time between the two. The masking threshold is the sound pressure level needed to make a sound audible to the human ear when in the presence of another sound known as a masker.
If the sound being masked exists beyond the masking threshold then it becomes audible and we hear it as a pre or post-echo. This most often occurs with sounds from percussion instruments but is likely any shorter transient burst of noise when encoded to a format such as MP3. There is a psychoacoustic element that means one often hears the pre-echo but not the post-echo. Forward temporal masking is much stronger than backward temporal masking which results in the post-echo being drowned out by the transient.
The effect of this is most noticeably heard on vocals, creating the illusion of the voice being double-tracked. The nature of perceptual audio coding is to remove frequency content that we are unlikely to hear. The result of this can sometimes mean that our perception of the remaining frequency content can be altered. The relative phase or timing of frequency content can be changed which can affect stereo imaging or even the transparency and clarity of the material.
One of the issues the MP3 format is most known for is making a banging bassline sound timid and weak. The amplitude of an analog signal is sampled at uniformed intervals, each sample is then quantized to the nearest value within a set range of digital steps. In a PCM stream, the amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps.
Bit depth refers to the number of possible digital values that can be used to represent each sample. Karlheinz Brandenburg , a professor at the Fraunhofer Institute was one of the lead developers of the MP3. By the late s, the MP3 was almost ready but still having issues dealing with the human voice.
Initially, MP3 compression absolutely destroyed the track leading to hundreds of revisions to get it right. The MP3 format still widely divides opinion but whether you think it saved the industry or ruined it, it certainly had a huge effect on it. There were some seminal moments in the history of MP3: the release of the Winamp media player for Windows in was huge.
The big change was that people could now have hundreds of songs on their computer without filling up their entire hard drive. In came Napster, the most infamous of the peer2peer sharing platforms which would be caught up in endless legal battles with most of the record industry.
Most mobile phones now have enough storage for all the music you can handle. It is an accurate, lossless format, the quality remains the same as the original recording. Files are easy to edit and process with user-friendly software from freeware to professional applications. Despite several advantages and disadvantages for each, the argument over MP3 or WAV will always come down to quality vs.
If you are an artist hoping to release a single, most online music stores require the WAV format. Imagine paying a mastering engineer to add the final polish then handing over an MP3 to work from.
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