How to read the band →
Solid line = floor (spellings that unambiguously belong to the group). Shaded band up to the dashed edge = ceiling (the most it could reach if every ambiguous spelling counted here).
Kyle
Kyle is now well below its former popularity. All-time it's been given to 494,713 U.S. babies, the 819th most common name by sound today, peaking at 22,947 in 1990, with 611 in 2025.
Kyle has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).