« Ada - der intelligente Raum » - Universität und ETH Zürich an der Expo.02


		Fundamental principles
		Sensory organs
			Touch
			Sight
			Hearing
			Smell
			Taste
		Processing data
		Interaction

Human sense of hearing

Using our ears, we are able to detect sounds from our environment within a certain frequency range. In addition, the inner ear also contains our organ of equilibrium. For human beings, the sense of hearing is quite essential since oral communication would not be possible without it: The articulation of sounds would be of no use, as they could not be picked up by a sensory organ.



Sectional view of the human ear

All noises generate sound waves (oscillations of the air), which are picked up by the ear. The sound waves strike the tympanic membrane, or eardrum, which starts oscillating in the corresponding frequency and intensity. The auditory ossicles of the middle ear amplify these oscillating motions and transmit them to the oval window. From the oval window, the oscillations are transmitted to the liquid that fills the inner ear. The oscillations are detected by so-called hair cells and translated into electrical impulses. These are then conveyed to the brain, where they get processed.

Stereophonic hearing

The auditory threshold for a sound increases considerably when other sounds are heard at the same time. Humans and animals hence have the ability to detect unexpectedly rapid changes in volume. Having two ears, we are able to make use of the stereo principle to localise the source of noises.

Ada’s auditory system



Ada’s ears – microphones

By means of ceiling and directional microphones, Ada is able to localise, identify and analyse sounds. She can filter out interesting individual noises from a noisy environment through her ability to detect rapid changes in volume. If a special noise is discovered, Ada has to determine where it is coming from. To do so, she makes use of ceiling microphones, which are continually listening for interesting sounds in the surrounding environment. Once such a sound is registered, the signals picked up by the different microphones are compared to then compute the most likely source of the sound.

Hearing with high sound intensity

As the sound intensity within the space is continually changing, Ada’s ability to discover sounds and react to them changes as well. In the case of high sound intensity, visitors might have to clap their hands to get Ada’s attention while speaking at a normal volume will suffice in the case of low sound intensity. In registering sounds, Ada measures the frequency, the pitch and the duration of the signal.

The directional microphones are only active when Ada directs her attention at a visitor. These microphones then try to collect acoustic data about this person. Ada is able to learn certain sound patterns (such as hand clapping or the name «Ada») and associate them with certain behavioural patterns.

When Ada detects a salient sound, she localises this person and turns her attention to the individual. She indicates this, for instance, by directing a spotlight at the person.

Ada is not able to understand the gist of words or whole sentences.