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Blind Assistant Free
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Description:
'Blind Assistant Free' turns your Android phone into a sonar employing a speaker to emit the sound pulses and a microphone to record the return echoes. This application is part of a research project that has the ambition to develop a modern echolocator ables to operate at not ultrasonic frequencies. The employed technology uses the same physical principles used by bats for orientation and hunt. Just point your phone in the direction you are walking to detect the presence of nearby obstacles and estimate their distance.
Thanks in advance to all users who wish to participate in this social project by sending reports and suggestions to improve the application. If the hardware of the phone does not support the minimum requirements, you can use an external device.
Read more
Features:
1) FREE 2) Fast and reliable algorithm
3) Immediate start by double clicking
4) Advanced Setting
5) User friendly program
6) Professional Handbook for users
You can find the free version of the program 'Blind Assistant Free' on Google Play Store.
Important notice:
1) The multimedia speaker should be oriented in the same direction of the obstacle to be detected.
2) Don't cover the microphone with fingers or hands.
Privacy Policy
These are our official statements regarding privacy in the use of our application (Blind Assistant Free) and this website (www.phonescience.eu).
'Blind Assistant Free' requires the network permission to send reports about the program efficiency. Reports can be sent only under user permission and will be used only for scientific purposes. Google Checkout's privacy policy is available at checkout.google.com/files/privacy.html.
This website uses Google Analytics to gather traffic information and demographics. This may include storing cookies with your web browser. The Google Analytics privacy policy is available at www.google.com/intl/en/analytics/privacyoverview.html.
This policy was lasted modified September 28th, 2014.
Please contact us for any further information.
User Manual
This is a product developed by Phone Science http://www.phonescience.eu
For contact and suggestions write to: info@phonescience.eu
Index
(1) Echolocation test
(2) Program controls
(3) Introduction
(4) Before starting
(5) Using
(6) Setup
Echolocation test
The echolocation test checks the hardware compatibility of your phone and it takes just few seconds of your time. During the test the program determines the intensity of the return echo at a fixed distance from the wall.
Only four simple things are required:
Choose a quite place.
Press the start button.
You need to approach to the wall. During the approaching you will hear the decreasing of the volume and finally at 40-70 cm from the wall you will hear the proximity alarms. Note that at less than 40 cm, there is a shadow area not covered by the echolocation. When you hear the first alarm, you should enter and exit from the shadow area a few inches from your location to allow the signaling of other proximity alarms.
Fig. 2
At the end of the test, a dialog box appears. Clicking on the button "Send" you will send a report containing useful information of the phone performance for echolocation.
Program controls
Controls are managed by buttons, seek bars and Spinners. Visual impared people can use talkback to manage all program functionality.
Introduction
This manual was written for sighted people that can help blind users to understand how this program works. Sounds can be reflected in the environment to produce echos. The return echos can be analyzed to calculate the position of objects. Like a bat hunts its prey, this natural ability has been reproduced into a cellular phone.
BlindAssistant represents a new research project to develop a low-cost and modern echo locator that requires only the conventional hardware inside a cellular phone. Practically, this App turns your phone into a portable equipment to detect any movements and objects close to you.
Before starting
Although BlindAssistant is provided by an auto setting system, the efficiency of this program could be negatively affected by the following factors:
(1) Different cellular phones are equipped by different hardware and some devices are better than others to analyze the return echo.
(2) The echolocation is more efficient if the direction of emitted pulses form an angle of 90° on the reflective surface. This principle is showed in fig. 1.
Fig. 1
(1) Ultrasounds are not supported on a cellular phone because both audio recording and sound playing are limited in bandwidth. The perfect discrimination among emitted signals and background noise is still difficult because the noise filters must operate at bandwidths not far away from ones used to detect echo. This means that the background noise may affects the sensitivity of echolocation. If the hardware of your phone doesn't support the minimal requirements needed by our program you can use an external device.
Read more
Despite the noise problems, Blind Assistant can be used inside rooms and open space places if the background noise does not exceed acceptable levels.
(2) The maximum detecting range depends by the maximum volume supported by your phone, so also in this case some phones will result better than others to locate distant objects.
(3) The following table show the minimal hardware requirement.
Media recording
Media Playing
Processor
RAM
44-48 KHz
44-48 KHz
1 GHz
512Mb
(4) Cellular covers may interfere with echolocation. For instance, some covers may improve the focusing of emitted pulses (positive effect), while other ones may cause an audio resonance (negative effect).
(5) In certain conditions, the wind can cause a noise that negatively affects the signals detected by the microphone.
Using
Blind Assistant uses your media microphone to record the return echo and the speaker to emit pulsed sounds. The microphone and the speaker should not be covered by fingers or hands otherwise, the program will not work optimally. After the acceptance of the license you will start echolocation double clicking on the display or clicking on the 'Start' button from the 'Start' section or directly from the 'Main' section. Each section will be introduced to you by a voice or sounds.
If you want to close the application click the System button "Back". A sound will signal that the application has been closed.
At the first use, (see Fig. 2) you can check the correct working of the program to get closer to a wall with the phone facing it. Near the wall the program will decrease the volume of output pulses and at a distance of 40-70 cm will produce a vibration or a proximity alarm (it depends by setting). The absence of alarms means that the setting is not optimal, or the phone does not fulfill the hardware requirements (see Setting). The free version of the program allows to do this test automatically.
The narrow corridors or certain positions within a room can facilitate a sound resonance that may causes false proximity alarms. This problem can be reduced changing the setting according to your preferences.
The max range for echolocation can be set pressing the volume media buttons in the "Start” section. You can select a range of 1, 2 and 3 meters that will be confirmed by a voice after their selection. This selection can be done also clicking on the associated buttons in the 'Start' section.
This setting also increases the minimal distance to enable the proximity alarm.
There are two ways to use this application:
In the first, you should point your phone in front of you in the direction of the obstacles to be located.
In the second you should point the phone towards the floor at an angle of about -45° referred to the horizon.
After a short adaptation phase you will be able to realize the changes in volume caused by close and distant objects only basing on sounds. In a more advanced step, you can change the settings of the program in order to obtain a refined modulation of the sound volume.
In small rooms or generally indoors, you need to decrease the maximal distance to detect the return echo to 1 or 2 meters. In this way you will avoid to listen the proximity alarm caused by nearby obstacles or resonance effects.
Setup
In the setup section you can set the main parameters that allow to adjust the sensitivity, precision and reactivity of the program. For simplicity we can classify the parameters in two categories: that ones affect the sensitivity of echolocation and that ones affect the precision of echolocation. In general these two classes of parameters have opposite effects.
Echolocation sensitivity
(Sensitivity and precision):
according to the user preference there are 3 different settings. “Standard” is the default.
Optimization
(Precision):
pressing the 'Optimize' button the 'Wave phase' will be adjusted according to your hardware. You will return to the default values pressing the 'Reset' button.
Vibration
: By default the proximity alarm is signaled by a sound but you can set a vibration. Please, select the check box 'vibration' to change this setting.
Sound Fx
: If you want to disable the sound effects don't select the 'sfx' check box.
Speaker and microphone input lines
: The default setting for speaker and microphone is “Multimedia”. Mainly, both devices are located on the rear of the phone. For particular purpose you may choose “Voice”, but in this case the proximity alarms will be signaled with a vibration.
Note:
the best setting should consider the equilibrium between sensitivity and precision. This equilibrium strictly depends by both hardware and the design of your phone.
Sound Pulses per second
(Sensitivity):
It sets the number of pulses per seconds. By default this parameter is set to 20Hz. If you increase this value both sensitivity and CPU requirement will increase.
Sound pulse width
(Sensitivity):
this is the set for the pulse width. By default this value is set to 200 mcSecs. Its changing could affect the sensitivity of echolocation positively or negatively, it depends by the hardware.
Power of emitted sounds
(Sensitivity):
the power of emitted sounds affect the max distance of objects detection (Max Volume). The "Min Volume" represents the minimal volume to be considered during the volume modulation. In cases of strong noise this parameter must be set to a suitable value. (see "Volume modulation on/off" to disable the volume modulation).
Enable or disable the volume modulation
(Sensitivity):
if you disable the “Volume modulation On/Off”, the program will signal only the proximity to an object. It could be useful in open space places when the high level of background noise makes the volume modulation not perceptible.
Equilibrium of true and false positive signals
(Sensitivity and precision):
this parameter takes effect on the time necessary to signal an obstacle. Before signaling an obstacle, the application considers the equilibrium of true and false positives signals. If you increase this parameter the necessary time to reach the equilibrium increases proportionally (more time and less false signals). If you will reduce this value the program will be more sensitive but less precise.
Distance filter
(Sensitivity):
This parameter allows to consider only objects inside the selected distance. The max value is 4 m. This parameter is useful in the case of small environments with short distance among objects.
False positive signals filter
(Sensitivity and precision):
false positive signals are minimized by this parameter. If you increase this value you increase the sensitivity to detect both small and far objects. In this case the ability of the program to filter false positive signals decreases progressively.
Signal level threshold
(Sensitivity and precision):
this is the threshold that acts on signal levels. If you increase this parameter, the sensitivity of the program and false signals decrease progressively.
Low pass filter
(Sensitivity and precision):
the low pass filter reduces the effect of the background noise when the sound frequency is higher than the set value. This parameter has a strong effect on sensitivity and accuracy.
Recording time
(Sensitivity, CPU and RAM demanding):
the recording time increases the information available for the echo analysis. The increasing of this parameter improves the sensitivity of the program but also increases the minimal amount of RAM and CPU demanding required to analyze the recording data.
Speaker resonance
(Precision):
This is a filter to manage the speaker resonance. The speaker resonance makes difficult the detection of objects at very short range < 30-40 cm. Please, increase this parameter until the program stops detecting false signals (it is also managed by the 'Optimize' button).
Minimal distance for stable signals
(Precision):
the minimal distance for stable signals that not includes the speaker resonance. Used in the statistical analysis of echo signals.
Wave phase
(Precision):
'Wave phase' is a parameter that allows to adjust the sound pulses according to your hardware. You can set it manually, but it is also managed by the 'Optimize' button.
Approaching speed to the object
(Noise attenuation):
'Approach speed' allows to attenuate the noise effect on detected signals. Set to 70 means that the approach speed to the object must be less than 5 Km/h. Signals associated to an approach speed higher than the set value will be filtered.
Credits
Thanks to FreeSFX: http://www.freesfx.co.uk
