Decibel 10

Decibel 10 by SkyPaw Ltd. is a well crafted and free app to measure sound levels in decibels.  While this is certainly not the only sound level app, in my opinion it is the best. It has a beautiful and intuitive interface, making it simple enough for even elementary students to easily measure sound levels.  The app provides convenient comparison for the values obtained with short word descriptions for situations that typically have that sound level. The ability to record and export (e.g. as email attachment) the decibel values along with time information is a significant strength. With this app and a speaker system it would be easy for a museum to make an interactive display for users to become familiar with decibel readings.

I show a typical screen from the app here.  At the bottom of the screen it gives both the current dB level (in the centre), a recent peak value (to the right) and a maximum value recorded during the current session (on the left).  In the centre is an analog meter format visual display.  The meter scale shows values above 75 dB as red, and has a total range from 0 to 110 dB. One feature that I like is that at the top it gives in words a typical comparison - e.g. "average quiet home".  It also shows a graph of recent values - these are the sound level values (not a graph of the sound waveform).

You can output data from the app using the arrow icon at the top right.  This gives the option to email the values recorded in the current session as a zip file.  When the file is opened it is a text file with data in the format: "2012:02:21 05:46:41.044 average: 50.326469, peak: 50.326469" providing the date, time, and average and peak dB values.  A science teacher would complain about the inappropriate number of significant figures given in the dB values, so students should be warned of this.  The default settings give 10 samples per second, all of which are output to this file.

This recording feature allows students to carry the device around and record sound levels, and then export the results all as one file.  If the students note where they are at different times, they can relate the values to the sound levels in those locations.  As mentioned at the outset, the operation of the app is so straightforward that I can see appropriate use by students of all ages, and the general public.  At a more advanced level students might use the app to investigate how intensity levels decrease at different distances from a source, or study sound levels from two speakers driven with the same tone in order to quantitatively study interference effects.

A bit of background on decibels (dB).  The decibel is used to compare two power levels, with the dB difference being 10 times the logarithm of the ratio of the powers.  More specifically we use dB in sound to compare the sound intensity values (W/m²).  For example if one sound level was 1000 times another, that would be a 30 dB difference. With sound it is conventional to establish a reference level of 0 dB at an intensity of 1.0x10^-12 W/m², the approximate limit of human hearing. Decibels are named in honour of scientists, engineer and inventor Alexander Graham Bell (1847-1922).  Although born in Scotland, he emigrated to Canada at age 23.  Although he has a long list of inventions, he is best known as the inventor of the telephone.  A museum in his honour is in Cape Breton Island in Nova Scotia. An interesting tidbit: he was born without a middle name, and so wanted one that he was given a middle name for his eleventh birthday (named after a well liked Canadian staying in their home).

The app is developed by SkyPaw Ltd., which also produce apps for timers, seismometers, a calculator and a metronome, among others.

My overall rating: 9 (out of 10).  I think that the app is near perfect, and particularly for a free app, is impressive.  I would like to see a more appropriate numbers of significant figures in the dB output in the export file, and if it were possible to somehow include annotations that would be exported with the file that would be great. So whether you want to have your students explore noise pollution, provide evidence to your apartment neighbours that they are too loud, or convince your spouse or children that they have the stereo or television too loud, this is a fun and useful app.  A few of those commenting on the app store report issues with the iPhone 4s that I have not been able to check. It certainly has worked flawlessly for me on an iPad 2 running the most recent iOS.  According to the developer it runs on iPad, iPhone and iPod touch, requiring iOS 3.2 or later.

Molecules

The app Molecules by Sunset Lake software renders 3D visualizations of molecules. The images are beautifully displayed, and the updating is incredibly fast and fluid even with complex molecules. This is a mature app that has been around for some time and has gone through a number of improvements.

There are two motion settings (changed with a button on the top right), one in which the image slowly rotates and the second a manual mode in which you drag your finger across then iPad (or iPhone) to see the molecule from any perspective. I particularly like the second mode when I am speaking to a class or group (with the Apple Digital AV adapter the iPad 2 display can be mirrored to a HD TV or monitor via a HDMI cable).

A control on the top right of the Molecules app display allows switching between space-filling and ball and stick representations. You can use two finger pinch to zoom in or out, and as mentioned a single finger drag to set viewing angle.

You can store a variety of molecules and easily switch between them from a list. This is particularly valuable for talks and lectures where you can set it up in advance. One user note, you only get the molecule list when in landscape mode.

The app comes with a few complex molecules pre-installed. Some
reviews have unfairly claimed that the software is not suitable for teaching about simple molecules. It is an easy job to import new molecules from either the PubChem or Protein Data Bank libraries. You start by pressing (when in landscape mode) the + button (top left), then select the database. For general use select the PubChem database, then simply enter the word for the chemical or category, and it will give you a list of molecules to select for download.

To remove molecules from the list, select landscape mode, then press Edit in the top left and then delete one or more molecules. One can enter molecules manually using either URLs or the iTunes interface. I have not tried this feature.

There is some additional text information included for most molecules, which is brought forward by using the blue triangle by the name of the molecule. As well as the structural information, the journal reference is given for most complex structures.

This wonderful app was created by Brad Larson of Wisconsin. He is Chief Technology Officer at SonoPlot, Inc., a company that designs microscale fluid dispensing systems. Sunset Lake Software is his part-time venture that does application development and software consulting. Brad Larson has an undergraduate degree in chemistry and a PhD in materials science.

I have used Molecules on both my first generation iPod Touch (updated to iOS 3.1.3) and on my iPad 2 and it works flawlessly on both, so I presume it works on intermediate models as well. The app is free, and the source code can be downloaded under the BSD license.

As a university instructor I see huge potential for this app. Rather than telling students about molecular structures, Molecules can be used in a guided inquiry mode. Let students examine complex molecules from different perspectives and answer a series of questions to predict properties from structures, or to compare two similar molecules.

The Molecules app is indispensable to researchers and educators who need to present molecular structures. Students will find it an excellent resource, especially in courses such as organic chemistry or biochemistry. Considering that it is free, it is an incredibly elegant display of molecular information. I rate it at 9 (out of 10). There are few apps that as impressively demonstrate the power of iOs devices. Why not try Molecules out for yourself by downloading it here?