WAV File Tips & Tricks

Identifying Major Features of a WAV Sound File

Deciding which sounds to use to create a Haptic effect can be very subjective as different effect designers may think some aspects of the sound are more important than others. Deciding where within the sounds Timeline to add the Haptic events is also subjective and part of the creative process.

There are, however, some key points to consider when deciding when and where to use Haptic effects with WAV files:

• Sudden volume changes. For example, this can be a gun shot or a crack of thunder. Good effects for these types of sounds are usually very strong, abrupt vibrations, or jolts. Sudden periods of silence may also need to be set off by a conspicuous absence of vibration. For maximum effect, planning for time when the device remains still is just as important as determining when and how it vibrates.



• Gradual volume changes. Some sounds can swell or fade gradually. Haptic effects for this type of sound should follow the same general rhythm. Some sound effects are musical and have a definite rhythm and meter. You can also create effects that follow the rhythm of the melody, bass drum beats, cymbal crashes, or even riffs in the horn line. Use effects that have expanding or fading magnitude envelopes to match these increasing or fading volume changes.



• Prominent frequencies or pitches. The sound of tires squealing as a car rounds a corner is an example of a very high-pitch sound you can accent with a high speed vibration. A fog horn is a very low frequency noise, and a low speed rumble is suitable, however, you should not base the speed of the vibration solely on the pitch of the corresponding sound. Low- to mid-motor speeds on a haptic device often feel stronger than high motor speeds. So, a particularly loud, high-pitched sound may require a strong, medium speed vibration.



• Tonality. Some sounds have an eerie or dissonant quality that you can accentuate through haptics. High frequency vibrations that gradually swell can give a similar eerie effect. Other sounds may be peaceful or even happy. In these instances, short-duration, "bouncy" effects may be more appropriate.



• The physical action the sound represents. Many sounds represent some real-world actions that are being simulated in a virtual world. This includes gun shots, earthquakes, picking up items, opening doors, etc. Firing a gun produces a loud bang and strong kick, so a matching effect would be a very strong, abrupt vibration. If a silencer is added to a gun the sound will be muffled, but the jolt that is felt may be just as strong as before. Thus, a strong effect may be appropriate even though the sound is not strong.



• Keep it simple. Don't overlap more than two Haptic events (effects) in a Timeline. If more than two Haptic events overlap, the effect will feel blurred. The distinct frequencies or magnitudes for each effect component will be lost as the dominant lower frequencies and higher magnitudes blanket any overlapped higher frequencies or lesser magnitude events.



• Filling in the blanks. If the sound file is complicated with many audio elements being heard at the same time, you will likely choose the louder, more dominant notes or sound accents to add Haptic events to in your Timeline. However, in some cases, there may be a fairly large time gap between these dominant sound events. If the gap between the events in the Timeline exceed, for example 500 ms, haptics should be applied to other ambient notes or sounds as well. Do this by adding low-magnitude effects that will help to fill in the gaps but will not give too much emphasis to these background notes or sounds.