Sound Card: Key Features


The name says it all: the sound cards are the devices responsible by providing the audio generated in your computer. At the beginning of the the era of PCs, this item is not existed – the only device sound present in some computers was the “PC Speaker”, used until today to issue a warning beeps from the motherboard. But, it didn’t take long for the sound cards that are becoming common. Today, it is hard to even find a motherboard new that does not have a integrated sound card (onboard). In this article, you will learn about the main features of the sound cards and, from this, you will have the means of evaluating the various models of this component are available in the market.

Characteristics of sound cards

The converters ADC and DAC

The sound cards are comprised by devices with one or more chips are responsible for processing and issuing of audio generated by applications. For this to be possible on the computers, it is necessary to work sound signals digital. It is at this point enters the scene the converters called ADC(Analog-to-Digital Converter – Analog-Digital converter) and DAC (Digital-to-Analog Converter – Digital-Analog Converter).

To the ADC (also known as The a/D Converter) it is up to the task scanning of the sound signals. The sound card receives these signals from an external device, for example, a microphone or a musical instrument. The sound from these devices is made available for analog signals. However, computers only work with digital information, and it is necessary, therefore, to make a conversion from analog to digital. Is exactly what the ADC does.

To hear the sound emitted by computers, we connect to the adapter sound speakers or headphones. For the audio get up to our ears by these devices, it is necessary to to do another conversion: the digital signal (that is, the signals worked by the machine) for analog signals. This task is done by the DAC (also known as Converter D/A).

It is clear that there are situations in which it is need to work with both converters to the same. This is possible on most sound cards, in a feature called full duplex.

Resolution of the sound cards

It is common to find in the specifications of the cards sound indications that suggest that the device works the 32 -, 64 -, or 128-bit. In fact, the majority of the cards sound works with resolutions of 16-bit (the older ones worked just with 8 bits), with the exception of some more sophisticated models that can work with more bits.

The numbers that are greater than 16 provided in the specifications, usually indicate the amount of tones are simultaneous to the plate can work (polyphony). The traditional 16-bit is sufficient to reproduce with a high sound quality to the sounds that we are able to hear, therefore there is the need to work with more bit. The cards that have 20-bit (or more) are generally used to avoid loss of quality in certain applications. This means that they have a high-fidelity sound, although not always see the difference.

Sampling rate

Many of the sound cards today are working with a sampling rate up to 100 KHz (approximately), and, depending on the model, this value can be much higher. But, what does this mean? To understand,note the wave graphic below:

The illustration represents a sound in analog form. As the computer only works with digital signals, it is necessary to to do a conversion, however, is not possible “capture” all the points of the signal. The frequency determines the interval between each point captured. The more points, the the more faithful will be the audio. See a comparison between the graphics below. Note that, with 11 KHz, the capture will be lower than 44 KHz, indicating that the audio quality will be lower:

The frequency response indicates the range of frequencies that the sound card can offer. In the most common devices, this range is between 20 Hz and 20 KHz, a value satisfactory to the human ears.

Depending on the frequency, there can be variances, this is, losses or gains. This parameter is measured in decibels (dB). Cards that feature this deviation in a rate of less than 1 dB (for more or less) are recommended to obtain a good quality of audio in the most diverse tones.


The SNR (Signal to Noise Ratio or Relationship Signal-to-Noise) indicates the level of the noise (a kind of interference) on the sound card. This area code is measured in decibels. Plates of good quality usually have SNR above 90 dB.

As to the THD (Tlike Harmonic Distortion or Total Harmonic Distortion), it is indicative of a level of distortion, in this case, a noise picked up during the transmission of the audio to the speakers or to the headphones. This measurement is made in percentage, and the smaller this value, the better.

It is curious to note that it is not always the manufacturers indicate the values SNR and THD. Generally, these rates are only specified when the sound card has very good quality.

Synthesizers and MIDI

When a sound is generated on the computer, the final file is usually become very large, making it necessary to use formats audio compression (like MP3 and Ogg Vorbis) and, mainly, synthesizers. These are “guided” by a default known as MIDI (Musical Instrument Data Iinterface).

The MIDI files are very small, if compared to the formats traditional audio. This is due to the fact that this format contain, in fact, sequences of musical notes. So, it is up to the synthesizers the task of following these sequences to generate the audio.

The synthesizer FM (Freqüência Modulada) it is one of the most common, as it allows the generationaudio in the sound card without the need to use audio scanned. The sound effects to existing games, for example, can be generated this way.

To ensure a sound more real, the sound cards also can use a type of synthesizer known as a Wave Table. Through him, it is possible to make audio through of samples from the instruments real sound. In this case, the samples can be saved in an own memory card sound. This synthesizer can also be emulated by software.

DSP (Digital Signal Processor)

The DSP is an important item for the quality of the audio, therefore, your presence is practically mandatory in sound cards more sophisticated. This is a dedicated chip to process sound information, freeing up the processor of the computer in such a task. The DSP is especially important in editing audio, since that makes faster the application effects and other handling features.

Some motherboards superior quality have DSPs built into them. This is important to avoid that the user have to buy a sound card offboard (that is, a sound card is “separate”, not integrated into the motherboard) due to a lack of quality audio onboard.

Audio channels

The audio channels indicates how many speakers you can connect on the board. The most simple support two channels, that is, the left and right channels. Adapters that support, for example, the technology Surround, they tend to have extra channels to provide a better use of such a resource.

What you want to say so, sound systems 5.1, for example? This the number indicates that the sound card is able to work with acoustic kits consisting of five speakers and a box subwoofer (used for bass tones). The same goes for kits 6.1 and 7.1.

Worth mentioning, however, that the expression “audio channels” you can also make reference to the amount of sounds that the card can run at the same time (already mentioned polyphony).


The sound cards can have multiple types of connections, everything depends on the model and the purpose of use of the device. The list below shows the most common connection types:

– MIC: microphone input;
Line In: input to connect audio equipment, such as a radio, for example;
– Line-Out: input to connect speakers or earphone;
Speaker: in this entry, you can connect loudspeakers without amplification;
– Joystick/MIDI in: input to connect a joystick control (for games) or MIDI instruments;
– SPDIF: input for connection of external devices.

In the case of connection to SPDIF (Sony/Philips Digital Iinterface), it is worth a note: in this standard,in fact, it is composed of several types of connection, one of them serves to connect a CD/DVD drive to the sound card, doing this has the task of converting the digital signals to analog audio from music CDs. In addition also, the SPDIF can also use connectors, optical and coaxial, where you can connect, for example, a home theater.

As shown in the table below, by convention, is to apply colors to each connection. These colors can be applied on the devices to be embedded, so it is easier to find what the correct entry for each one. Worth mentioning, however, that not all cards that use this scheme. Here in AbbreviationFinder, for example, already been tested a card Sound Blaster X-FI Platinum, whose fittings were gold.

As stated at the beginning of this article, almost all of the motherboards current come with integrated sound card. This is good, as that represents an expenditure unless in the purchase of a computer. On the other hand, you should observe the characteristics of the audio offered to not buy a low quality product. Motherboards top quality usually offer a good audio system.

Now, if what you want is a sound high-fidelity and compatible with the technologies latest audio,have no doubt, buy a sound card quality. So you will have a great experience to listen to your songs, play your games favorite, watch a movie and, if it is your case, work with audio editing. Do not forget to use speakers or headphones quality to take advantage of everything that your sound card offers!

Sound Card Key Features 1

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