Question: What is the register used for falsettone?

Context paragraphs:
X86 debug register: On the x86 architecture, a debug register is a register used by a processor for program debugging.  There are six debug registers, named DR0...DR7, with DR4 and DR5 as obsolete synonyms for DR6 and DR7.  The debug registers allow programmers to selectively enable various debug conditions associated with a set of four debug addresses.

Carry flag: In computer processors the carry flag (usually indicated as the C flag) is a single bit in a system status (flag) register used to indicate when an arithmetic carry or borrow has been generated out of the most significant ALU bit position.  The carry flag enables numbers larger than a single ALU width to be added/subtracted by carrying (adding) a binary digit from a partial addition/subtraction to the least significant bit position of a more significant word.  It is also used to extend bit shifts and rotates in a similar manner on many processors (sometimes done via a dedicated X flag).  For subtractive operations, two (opposite) conventions are employed as most machines set the carry flag on borrow while some machines (such as the 6502 and the PIC) instead reset the carry flag on borrow (and vice versa).

Test register: A test register, in the Intel 80386 and Intel 80486 processor, was a register used by the processor, usually to do a self-test.  Most of these registers were undocumented, and used by specialized software.  The test registers were named TR3 to TR7.  Regular programs don't usually require these registers to work.  With the Pentium, the test registers were replaced by a variety of model-specific registers (MSRs).

Overflow flag: In computer processors, the overflow flag (sometimes called V flag) is usually a single bit in a system status register used to indicate when an arithmetic overflow has occurred in an operation, indicating that the signed two's-complement result would not fit in the number of bits used for the operation (the ALU width).  Some architectures may be configured to automatically generate an exception on an operation resulting in overflow.

Classical Chinese grammar: Classical Chinese grammar is the grammar of Classical Chinese, a term that first and foremost refers to the written language of the classical period of Chinese literature, from the end of the Spring and Autumn period (early 5th century BC) to the end of the Han Dynasty (220 AD).  The term "Classical Chinese" is also often used for the higher language register used in writing during most of the following centuries (a register generally referred to by sinologists as "Literary Chinese"); however, this article focuses on the grammar used in the classical period.

Damin: Damin "(Demiin" in the practical orthography of Lardil) was a ceremonial language register used by the advanced initiated men of the aboriginal Lardil ("Leerdil" in the practical orthography) and the Yangkaal peoples of Australia.  Both inhabit islands in the Gulf of Carpentaria, the Lardil on Mornington Island, the largest island of the Wesley Group, and the Yangkaal on the Forsyth Islands.  Their languages belong to the same family, the Tankic languages.  Lardil is the most divergent of the Tankic languages, while the others are mutually comprehensible with Yangkaal.

Index register: An index register in a computer's CPU is a processor register used for modifying operand addresses during the run of a program, typically for doing vector/array operations.

Falsettone: Falsettone is a term used in modern Italian musicology to describe a vocal technique used by male opera singers in the past, in which the fluty sounds typical of falsetto singing are amplified by using the same singing technique used in the modal voice register.  The result is a bright, powerful tone, often very high-pitched, although the sound is still different from and more feminine than what is produced by the modal voice.  The term "falsettone" is also used for the mixed vocal register that can be achieved using this technique.

Negative flag: In a computer processor the negative flag or sign flag is a single bit in a system status (flag) register used to indicate whether the result of the last mathematical operation resulted in a value whose most significant bit was set.  In a two's complement interpretation of the result, the negative flag is set if the result was negative.

Modal voice: Modal voice is the vocal register used most frequently in speech and singing in most languages.  It is also the term used in linguistics for the most common phonation of vowels.  The term "modal" refers to the resonant mode of vocal cords; that is, the optimal combination of airflow and glottal tension that yields maximum vibration.

Supporting paragraphs: Falsettone Modal voice
Answer: Modal voice