A skin drum pitches higher as its head is pulled tighter, with frequency rising as the square root of tension, so raising the note an octave needs four times the force on the hoop. Make the head only from the hide of an animal whose health you knew, because untreated hide and hair from unknown animals can carry anthrax spores. Stretch the hide wet, lash it to a hoop strong enough for the load, and let it dry slowly.
Part of Music & Simple Instrument Making
Frame drums and goblet drums with a stretched hide head: how tension sets pitch, how to size the hoop, and how to source hide safely.
Pitch Follows Tension And Size
Tapping a drumhead excites a pattern of vibration whose lowest mode, for an ideal circular membrane, has a frequency f = (2.405 ÷ 2πa) × √(T ÷ σ), where a is the head radius in metres, T is the tension per unit length of rim in newtons per metre, and σ is the head’s mass per unit area in kilograms per square metre. The constant 2.405 is the first zero of a standard mathematical function (the Bessel function J₀). It is an idealisation: a real drum has air loading, stiffness and a hole or cavity, so treat the result as a first estimate.
Three consequences are robust whatever the idealisation:
- Pitch rises as the square root of tension. Doubling the pitch (one octave) needs four times the tension; raising it a whole tone (frequency ratio 9:8) needs (9÷8)² = 1.266 times the tension.
- Pitch falls as the head gets larger. At the same tension and head material, a 40 cm drum sounds at 30 cm ÷ 40 cm = 0.75 of the frequency of a 30 cm drum, which is 1200 × log₂(0.75) = −498 cents, about a fourth lower.
- A heavier head sounds lower. Thick hide is slower than thin hide at the same tension, which is why the parent article prefers thin skin (rabbit, goat) over thick (cow, deer).
Worked Example: Loads On A 30 cm Frame Drum
Take a head radius a = 0.15 m, a hide 0.5 mm thick (0.0005 m), and a hide density I recalled as about 1,100 kg/m³ (not sourced; weigh your own hide to check). Then σ = 1,100 kg/m³ × 0.0005 m = 0.55 kg/m². For a target note of f = 100 Hz:
- T = σ × (2π × a × f ÷ 2.405)² = 0.55 × (2π × 0.15 × 100 ÷ 2.405)² = 0.55 × (39.2)² = 0.55 × 1,536 ≈ 845 N/m
- Rim length = 2π × 0.15 m = 0.942 m, so total pull = 845 N/m × 0.942 m ≈ 796 N, which is 796 ÷ 9.81 ≈ 81 kilograms-force
- Compression in the hoop ring ≈ T × a = 845 × 0.15 ≈ 127 N
- Stress in the hide = 845 N/m ÷ 0.0005 m ≈ 1.69 MPa
Air loading lowers the real pitch below this ideal, so reaching 100 Hz in practice needs at least this tension, and the hoop must be built for that. 796 N at the rim is a serious load for a lashing, which is why thin cord rubbed through punched holes fails; use broad lashings or a sewn rawhide edge, and test the lashing before you trust it. I have no sourced figure for the strength of rawhide or cord, so test samples; see Rope Strength Testing.
What You Need
- Hide from a known animal — slaughtered healthy, ideally by you; thin hide is easier; see Hide Preparation
- A hoop — green wood bent to a circle 20-40 cm in diameter, as the parent article says, overlapped and lashed
- Cordage for lashing; see Two-Ply Twist
- For a goblet drum: a hollowed trunk, narrow at the base and wide at the head; see Log Drums & Hollow Trunk
Method: Frame Drum
Step 1: Prepare the hide. Scrape off flesh and fat, soak in water overnight, and keep it wet. Never use a hide of unknown history.
Step 2: Stretch evenly while wet. Pull around the rim in opposite pairs, a little at a time, so tension is uniform. Uneven pulls make the drum sound dull and the head crease.
Step 3: Lash to the hoop through small holes punched back from the edge, so the hide cannot tear out at the margin.
Step 4: Dry slowly in shade. The hide shrinks and tightens as it dries. Rapid drying near a fire makes it brittle.
Step 5: Tune. Dampness slackens a head and dry air tightens it, so a drum goes flat in humid weather. Warm the head gently to raise the pitch; do not scorch it.
Common Mistakes
- Pulling the hide tight in one corner first. The head wrinkles and the tension is uneven.
- Thin cord through thin hide. The lashing cuts out.
- A hoop that is too light. The ring crushes inward under the 127 N compression above.
Safety
Anthrax in hide and hair
Anthrax spores survive in dried hide and hair for very long periods. In the nineteenth century people who sorted wool and hides suffered it as an occupational disease, and drum-makers working with imported animal hides have developed it in modern times (reported by US health authorities in 2006; recalled, verify). Boiling does not reliably kill spores; see Pressure Sterilization. Use only hide from an animal you saw healthy at slaughter, never from one found dead, never dried hide of unknown source, and do not open a carcass that died suddenly with blood from its orifices; see Veterinary Medicine and Zoonotic Diseases. Cover cuts and wash after handling. Unknown provenance is the risk.
What’s Next
- Learn next: String Materials — gut and sinew carry the same hide risks
- Combine with: Rhythm Training — what to play once the drum is made