Norms Tutorial

This tutorial is available from within Sonneta by selecting Help > Norms Tutorial.

This tutorial familiarizes you with the Norm Library and working with norms. It assumes no prior knowledge of Sonneta. To understand how norms are used in your documents, follow the Essentials Tutorial.

In Sonneta a normative reference or "norm" is defined as the expected distribution of a measurement for individuals in a defined demographic group. These distributions will be demonstrated graphically below. The "demographic group" is characterized by age and gender and has no known pathologies. In addition, each norm in Sonneta is associated with the journal reference in which the study was reported.

Browsing and searching the library

A description of the Norm Library can be found in the onscreen Help.

  1. To view all norms in the Norm Library, select Norms > Open Library…
  2. Click on the “Fo (Hz)” item in the list of measurements in the upper left-hand portion of the window to show only Fo norms. The norms are listed in the table to the right.
  3. Click the "Reference" column heading in the norm table to sort norms alphabetically by reference.
  4. Click on a row of the right-hand norm table to select it and show a histogram for that norm.
  5. In the search field on the right-side of the toolbar, type "Campisi" to filter only norms with "Campisi" in the reference. (There is only one.)
  6. Select the "Voice" item in the list of measurements to see norms by Campisi for all voice measurements.
  7. Click the 'x' button in the search field to see all norms again. The search field searches text in the Reference, Algorithm, Task, Group and Comments table columns.

Interpreting norms

Sonneta uses colored bars to represent likelihood intervals.

  1. Select the “Fo (Hz)” item in the list of measurements again.
  2. Select the Campisi norm in the norm table. The chart below will show a bell-shaped curve of the expected number of individuals versus their habitual fundamental frequency in Hz. This Gaussian norm is an idealized distribution based on results reported in the Campisi reference.
  3. The colored bars above the curve show the fraction of individuals that fall within the likelihood intervals. To illustrate this, select Sonneta > Preferences… from the Sonneta menu, and then click the Charts tab.
    1. The Lower Level should be set to 75%. This means 75% of healthy individuals fall within the pitch range given by the green bar. Change this number to 30%, and press the return key. The green bar in the Norm Library chart will get much narrower.
    2. The Upper Level should be set to 90%. This means 90% of healthy individuals fall within the pitch range given by the yellow and green bars. Change this number to 99%, and press the return key. The yellow bars in the Norm Library chart will get much wider.
    3. Click the Use Defaults button in the lower-left corner of the Preferences window to restore the default values. You can also try clicking the color buttons in the Likelihood Intervals box to change bar colors. Close the Preferences window when you are done.
  4. Now select one of the Massachusetts Eye and Ear Infirmary norms for "Fo (Hz)" in the norm table. Instead of a bell-shaped curve, you will see a histogram. This is a data norm, and it contains much more accurate information than the idealized Gaussian norm. It is better to rely on data norms when they are available. Note that the colored bars representing likelihood intervals are not symmetric for data norms.
    1. Adjust the slider control at the bottom-right corner of the Norm Library window. This slider changes only the bin-width for the histogram display. It has no effect on the locations of the colored bars.

Comparing and combining norms

Sonneta allows you to graphically compare and combine norms from different references.

  1. Hold down the ⌘-key while selecting a few different norms in the norm table. The norms will all be charted together in different colors.
  2. Try selecting just the norms from the Lin, et al. reference. Notice how the norms for male and female subjects differ. (The 'M' and 'F' table columns denote whether the norm is derived from male or female subjects.)
  3. Select a few norms for males in a similar age range. (The age range is given by the "Min Age" and "Max Age" table columns.)
    1. Click the "Max Age" column heading to sort by maximum age.
    2. Click the 'M' column heading so that norms are sorted by sex first, and Max Age second.
    3. Select a few of the norms for males with a similar Max Age.
  4. Click the "Show Sum" checkbox at the bottom of the window so that it is checked. A gray histogram will be drawn showing the sum of all norms. The colored bars above the chart now show likelihood intervals for this combined histogram. 

This tutorial illustrates how to manually combine norms to create likelihood intervals that can be compared with measurements of your subjects. However, when you make measurements using Sonneta (as done in the Essentials Tutorial), Sonneta automatically selects appropriate norms and combines them for you. The session charts and history charts that Sonneta displays are color-coded according to the Preferences you have set here.

Further exploration

You can customize how Sonneta automatically selects norms for your subjects.