The following table shows some of the descriptors captured from the survey. Column 1 indicates the ratings associated with these adjectives. The rating scale range was from 1 ("poor") to 5 ("great"). A 3 would be considered neutral. For example, "Favorable" descriptors accompanied ratings of 4 or 5; "Neutral or favorable" descriptors were used with ratings of 3 or higher; "Unfavorable" descriptors were used with ratings of 2 or lower. The "Across all ratings" category is for descriptors accompanying all ratings (rating from 1 to 5).
open, hollow, edgy, brassy, overblown, diffuse, loud, soft, bright, dark
For this project, "upper harmonics" will be defined as harmonics 3-7 (H3-H7).
"Bright" and "dark" were often used by different participants to describe a particular sample. Although these terms seemingly have opposite meanings were they generally used with samples rich in harmonics.
Some terms like "sharp" (pitch vs. point/edge) or "soft" (loudness vs. not-hard vs. subtle) could be interpreted in different ways. There was often insufficient context to clearly interpret these adjectives.
The following chart shows the overall rating (1 = "poor", 5 = "great") for each audio clip. The survey consisted of 6 pairs of notes.
Legend for Harmonics in Spectral Charts
Each harmonic is represented as a line on the left half of each screen. The Y-axis indicates the strength or loudness (higher on the Y-axis means stronger). The following table shows the color coding for harmonics:
Fundamental (perceived pitch)
Octave above fundamental
Octave + fifth above fundamental
Two octaves above fundamental
Two octaves + third above fundamental
Two octaves + fifth
Two octaves + minor seventh above fundamental
Organization of the Results
The following sections show results for each pair of notes. The information is formatted as follows:
The pair number, pitch, and rating
Favorable - terms used with ratings of 4 or 5
Unfavorable - terms used with ratings of 1 or 2
The spectral chart (for additional information on how to read the spectra use the link at the bottom of this page)
Some notes and observations along with additional descriptors
The survey format implicitly encouraged participants to directly compare and contrast the two samples within each pairing. In some cases, the descriptors reflect the outcome (louder, fuller, airier, less-dark, more-focused, etc.). Comparing numerical ratings within a pairing valid. Some care must be exercised comparing ratings across different pairs.
Samples #3A and #5A was generally rated favorably (focused, clear, rich, strong) and received very few negative ratings. Sample #3A has a rich balance of harmonics. In contrast, sample #5A has fewer upper harmonics, but it is at a higher pitch and the tendency is for diminishing upper harmonics as the pitch rises (see the Spectra Comparisons page for more details).
Sample #3B, #4A, and #5B were generally rated neutral or unfavorable (unfocused, breathy, weak, airy) and received few positive ratings. These samples tend to have weak upper harmonics. The strongest harmonics are H1 (white/fundamental) and H2 (yellow/octave).
Sample #2B was generally rated neutral or unfavorable, but also received several positive ratings. Unlike #3B, #4A, and #5B, this sample was considered strong and focused. However, many felt that it was overblown or forced. It is worth pointing out that H3 (green) is very predominant.
Some samples, like #4B and #6B drew polarizing responses with ratings widely distributed from "great" to "poor". Samples in this category may reflect differences in "taste" among listeners.
Descriptors generally accompany samples that have relatively strong amounts of upper harmonics (H3-H7) include: bright/dark, vibrant, colorful, nasal, resonant, edgy, rich, brassy, trumpety, reedy, and focused. Trumpet and oboe spectra contain strong higher harmonics and may be viewed by using this link: trumpet/oboe
Sample #6A had an interesting and contradictory use of descriptors. The adjective "focused" was used with favorable, neutral, and unfavorable ratings. Similarly, the adjective "unfocused" (as in "slightly-unfocused", "a bit unfocused", "less focused", or "unfocused") was used with favorable, neutral, and unfavorable ratings as well. This unusual use of these terms was unique to sample #6A.
A pilot study with 19 university musicians had some interesting differences from the Flute List ratings. For example, some of the clips with very weak upper harmonics were rated much higher in the pilot. Clips rich in harmonics were rated somewhat lower in the pilot. 6 of the 19 participants were flutists, 9 were brass players, and the remainder were woodwind players. Since the sample size is small, it is difficult to draw conclusions. This does raise the question of whether highly trained flutist have different criteria for "good" flute timbre than non-flutists or flutist with less experience.
Results from the Flute List survey indicate a preference towards timbres rich in harmonics. However, the appropriate balance of harmonics is clearly important. For example, if H3 is disproportionate, the quality can become too harsh or edgy for some listeners. On the other hand, insufficient upper harmonics may be judged as too weak or airy. As pitch varies so does the harmonic spectra, therefore the criteria for an appropriate mixture of harmonics changes for each pitch. Additionally, musical context and taste plays a significant role. The survey contained two samples that demonstrated a wide range of ratings which may reflect differences in taste.
These are preliminary observations. The full thesis paper will contain more information.
For background information on harmonics use this link: background