00:00-47 – fixed pitch in different registers with one, two, three, four, and five valves halved, respectively
00:48-end – full-register glissando with one, two, three, four, and five valves halved, respectively
In half-valving, one or more valves are depressed halfway while attempting to produce ordinario phonation. As a result, there is a greater reliance on embouchure for determining pitch. Additionally, the timbre is changed, and the range of lip glissing increased significantly.
If the traditional sound of the tuba (ordinario) might be described as a spectrum from bright, focused tones in the highest register to dark, rumbling tones in lowest, this manipulation of hardware exerts a “muffling” filter onto that sonic field, giving it a veiled, hoarse quality. The sound lacks its usual robustness, and perhaps sounds a bit swallowed. It should be noted that while not perceptibly linear, the transition in number of valves halved from one to many is noticeable, especially when comparing the extremes.
Regarding glissando, the greater the number of valves halved, the wider the range. With all valves halved, it is possible to gliss the entire sounding range of the tuba with only one or two perceivable jumps.
Pitch range. Same as ordinario. Intonation is less consistent, because the partials are obscured. A player may become more confident with specific fingerings/embouchures with practice, but it will likely always be a struggle, if not impossible, to keep virtuosic, half-valved figurations from sounding sloppy and inaccurate.
Dynamic range. The lower end is the same as that of ordinario. The upper end depends on the number of valves halved: one valve allows for a maximum of ff, whereas all valves allow only for mf.
Practice tip(s). Try to keep a halved valve as close to halfway depressed as possible—that is, unless it is desirable to explore the spectrum from fully open (complete phonation) to fully closed (complete phonation, different fingering), with maximum obscuration of the partial in between.