Understanding What Makes Digital Sound Different from Analog Sound - dummies

Understanding What Makes Digital Sound Different from Analog Sound

By Ryan C. Williams

Remember when musical recordings were stored on cassettes or vinyl records? These recordings stored sound in an analog format — the sound was recorded to the disc or tape as physical grooves or magnetic impulses. The medium got the song from the artist to the listener, but it still had some drawbacks.

Ah, but then came the compact disc. Instead of being carved into the grooves of the record or recorded on magnetic tape, the music was encoded on the disc as numerical information. A laser reads the information and translates that into your favorite song. Music fans have their preferences — some people still insist on the superiority of analog sound. But digital music is here to stay.

The drawbacks of analog sound

The main drawback of analog recordings is that they tend to degrade each time they are played. When you pressed the Play button, physical contact was made between the recording and the player. Like rubbing sandpaper against wood, some of the detail on the recording would be worn away. Before long, you would start to hear the cracks and pops associated with old recordings. The music would get lost behind the noise, and fairly soon, you would need to go out and buy a new copy to get that wonderfully clear sound back.

Second, vinyl records were a little hard to carry around and listen to wherever you want. Unless you have a full stereo system available, it wasn’t easy to hear your records in their intended glory. Cassettes made the music a little more mobile with the advent of the portable stereo and the Walkman, but the sound wasn’t quite as good as that from the vinyl records. This was a symptom of the format itself — the tape on which musicians usually recorded their music was several inches wide to allow as much detail as possible to be recorded. After the sound had been mixed down to the small stereo tracks of a cassette (along with the requisite hiss that accompanies sound recorded on that cassette), it had lost a little something.

The benefits of digital sound

When you compare digital and analog sound, the first thing you need to examine is the sample rate. In analog recordings, the machine is always recording any sound or noise that is coming through the microphones. In digital recording, however, you don’t have a constant recording of what’s going on. Instead, you have a series of samples taken from the sound being recorded.

Think of it like a movie — a motion picture strings together a series of pictures to make it look like moving action. In this case, digital recording takes a series of “pictures” of what the sound is like and turns it into a digital recording. A standard compact disc contains sound that has been sampled at 44.1 kHz, or just over 44,000 times a second. However, you may run into digital sound on the Internet that’s been recorded at 48 kHz, 96 kHz, or even higher. Just think of it as getting more detail from more pictures.

But how do those pictures look? The more detailed those pictures are, the better the sound is. That’s where bitscome in. By increasing the number of bits (units of information) contained in the file, the amount of detail contained in each sample is increased. A standard CD has 16-bit sound, although you might occasionally run into higher bit sizes on the Internet.

Now consider the bit rate of the file. Digital music files are measured in the amount of information they play per second. In most cases, it’s measured in Kbps, or kilobits per second. This is the amount of sound information presented to the listener every second. The standard for near-CD quality is 128 Kbps, and some files go up to 320 Kbps. On the other hand, files played over Internet radio are 56 or 64 Kbps to allow faster transport over networks, like your dialup or broadband Internet connection.

In short, the benefits to using digital sound are the following:

  • Portability: You can take digital sound anywhere on a variety of devices, and you can transfer it from network to computer very easily.
  • Durability: Digital audio doesn’t degrade like analog audio sources.
  • Options: You can buy or record your audio in differing levels of quality and size, depending on your needs.
  • Sound Quality: Unless you’ve invested thousands of dollars in audiophile-quality analog audio gear, you’ll probably note a better sound coming from digital audio systems.